Solve Physics Problems

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1.1/3 points | Previous AnswersSerPSE8 2.P.010.My Notes |

Question Part

Points

Submissions Used

A car travels along a straight line at a constant speed of 41.5 mi/h for a

distance d and then another distance d in the same direction at another constant speed. The average velocity for the entire trip is 25.0 mi/h.

(a) What is the constant speed with which the car moved during the second

distance d?

Your response is within 10% of the correct value. This may be due to roundoff

error, or you could have a mistake in your calculation. Carry out all intermediate

results to at least four-digit accuracy to minimize roundoff error. mi/h

(b) Suppose the second distance d were traveled in the opposite direction; you forgot something and had to return home at the same constant speed as found

in part (a). What is the average velocity for this trip?

Your response differs significantly from the correct answer. Rework your solution

from the beginning and check each step carefully. mi/h

(c) What is the average speed for this new trip?

mi/h

2.–/3 pointsSerPSE8 2.P.013.My Notes |

Question Part

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Submissions Used

A velocity—time graph for an object moving along the x axis is shown in the figure. Every division along the vertical axis corresponds to 2.00 m/s and each

division along the horizontal axis corresponds to 2.50 s.

(a) Plot a graph of the acceleration versus time.

This answer has not been graded yet.

(b) Determine the average acceleration of the object in the following time

interval t = 12.5 s to t = 37.5 s. m/s2

(c) Determine the average acceleration of the object in the following time

interval t = 0 to t = 50.0 s. m/s2

3.–/3 pointsSerPSE8 2.P.016.WI.My Notes | A particle starts from rest and accelerates as shown in the figure below.

(a) Determine the particle’s speed at t = 10.0 s. m/s

Determine the particle’s speed at t = 20.0 s? m/s

(b) Determine the distance traveled in the first 20.0 s. (Enter your answer to one

decimal places.)

m

4.–/3 pointsSerPSE8 2.P.017.MI.My Notes |

A particle moves along the x axis according to the equation x = 1.99 + 2.99t − 1.00t2,

where x is in meters and t is in seconds. (a) Find the position of the particle at t = 2.50 s. m

(b) Find its velocity at t = 2.50 s. m/s

(c) Find its acceleration at t = 2.50 s. m/s2

5.–/2 pointsSerPSE8 2.P.020.My Notes | Draw motion diagrams for the following items. (Do this on paper. Your instructor

may ask you to turn in your work.)

(a) an object moving to the right at constant speed

(b) an object moving to the right and speeding up at a constant rate

(c) an object moving to the right and slowing down at a constant rate

(d) an object moving to the left and speeding up at a constant rate

(e) an object moving to the left and slowing down at a constant rate

This answer has not been graded yet.

(f) How would your drawings change if the changes in speed were not uniform;

that is, if the speed were not changing at a constant rate?

This answer has not been graded yet.

6.–/5 pointsSerPSE8 2.P.021.My Notes | A parcel of air moving in a straight tube with a constant acceleration of –

4.10 m/s2 and has a velocity of 13.5 m/s at 10:05:00 a.m.

(a) What is its velocity at 10:05:01 a.m.?

m/s

(b) What is its velocity at 10:05:04 a.m.?

m/s

(c) What is its velocity at 10:04:59 a.m.?

m/s

(d) Describe the shape of a graph of velocity versus time for this parcel of air.

This answer has not been graded yet.

(e) Argue for or against the following statement: “Knowing the single value of an

object’s constant acceleration is like knowing a whole list of values for its

velocity.”

This answer has not been graded yet.

7.–/3 pointsSerPSE8 2.P.024.MI.My Notes | We investigated a jet landing on an aircraft carrier. In a later maneuver, the jet

comes in for a landing on solid ground with a speed of 95 m/s, and its

acceleration can have a maximum magnitude of 5.52 m/s2 as it comes to rest.

(a) From the instant the jet touches the runway, what is the minimum time

interval needed before it can come to rest?

s

(b) Can this jet land on a small tropical island airport where the runway is 0.800

km long?

Yes No

(c) Explain your answer.

This answer has not been graded yet.

8.3/5 points | Previous AnswersSerPSE8 2.P.027.My Notes | A speedboat travels in a straight line and increases in speed uniformly

from vi = 12.5 m/s to vf = 41.5 m/s in a displacement Δx of 150 m. We wish to find the time interval required for the boat to move through this displacement.

(a) Draw a coordinate system for this situation. (Do this on paper. Your

instructor may ask you to turn in this work.)

(b) What analysis model is most appropriate for describing this situation?

particle under constant speed particle under constant acceleration particle in

equilibrium

(c) From the analysis model, what equation is most appropriate for finding the

acceleration of the speedboat?

vf = vi + at

Δx = vi + 1 2

at2

vf2 = vi2 + 2aΔx

(d) Solve the equation selected in part (c) symbolically for the boat’s acceleration in terms of vi, vf, and Δx.

a =

(e) Substitute numerical values to obtain the acceleration numerically.

m/s2

(f) Find the time interval mentioned above.

s

9.1/4 points | Previous AnswersSerPSE8 2.P.033.My Notes | An object moves with constant acceleration 4.10 m/s2 and over a time interval

reaches a final velocity of 12.8 m/s.

(a) If its initial velocity is 6.4 m/s, what is its displacement during the time

interval?

m

(b) What is the distance it travels during this interval?

m

(c) If its initial velocity is -6.4 m/s, what is its displacement during the time

interval?

Your response differs from the correct answer by more than 10%. Double check

your calculations. m

(d) What is the total distance it travels during the interval in part (c)?

Your response differs from the correct answer by more than 10%. Double check

your calculations. m

10.–/4 pointsSerPSE8 2.P.038.My Notes | An attacker at the base of a castle wall 3.90 m high throws a rock straight up

with speed 9.00 m/s from a height of 1.70 m above the ground.

(a) Will the rock reach the top of the wall?

Yes /No

(b) If so, what is its speed at the top? If not, what initial speed must it have to

reach the top?

m/s

(c) Find the change in speed of a rock thrown straight down from the top of the

wall at an initial speed of 9.00 m/s and moving between the same two points.

m/s

(d) Does the change in speed of the downward-moving rock agree with the

magnitude of the speed change of the rock moving upward between the same

elevations? Explain physically why it does or does not agree.

This answer has not been graded yet.

11.0/1 points | Previous AnswersSerPSE8 2.P.041.WI.My Notes | A ball is thrown directly downward with an initial speed of 8.65 m/s from a

height of 29.6 m. After what time interval does it strike the ground?

You know the initial velocity, the distance and the acceleration. Which equation

in Table 2.2 will allow you to find the time? You may need to use the quadratic

equation. s

12.–/1 pointsSerPSE8 2.P.042.My Notes |

The height of a helicopter above the ground is given by h = 2.80t3, where h is in meters and t is in seconds. At t = 1.70 s, the helicopter releases a small mailbag. How long after its release does the mailbag reach the ground?

s

13.2/4 points | Previous AnswersSerPSE8 2.P.043.MI.My Notes | A student throws a set of keys vertically upward to her sorority sister, who is in a

window 2.00 m above. The second student catches the keys 2.30 s later.

(a) With what initial velocity were the keys thrown?

magnitude Your response differs from the correct answer by more than 100%. m/s

direction

(b) What was the velocity of the keys just before they were caught?

magnitude The correct answer is not zero. m/s

direction

14.–/3 pointsSerPSE8 2.P.048.My Notes |

Question Part

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Submissions Used

A student drives a moped along a straight road as described by the velocity

versus time graph in the figure. The divisions along the horizontal axis

represent 1.0s and the divisions along the vertical axis represent 2.0 m/s.

Sketch this graph in the middle of a sheet of graph paper. (Do this on paper.

Your will need it to do part (a) and (b).)

(a) Directly above your graph, sketch a graph of the position versus time,

aligning the time coordinates of the two graphs. (Do this on paper. Your

instructor may ask you to turn in your work.)

(b) Sketch a graph of the acceleration versus time directly below the velocity-

versus time graph, again aligning the time coordinates. On each graph, show the

numerical values of x and ax for all points of inflection. (Do this on paper. Your instructor may ask you to turn in your work.)

(c) What is the acceleration at t = 6.0 s? m/s

(d) Find the position (relative to the starting point) at t = 6.0 s. m

(e) What is the moped’s final position at t = 9.0 s? m

15.–/5 pointsSerPSE8 2.P.053.MI.My Notes |

Question Part

Points

Submissions Used

An inquisitive physics student and mountain climber climbs a 54.0-m-high cliff

that overhangs a calm pool of water. He throws two stones vertically downward,

1.00 s apart, and observes that they cause a single splash. The first stone has an

initial speed of 1.88 m/s.

(a) How long after release of the first stone do the two stones hit the water?

s

(b) What initial velocity must the second stone have if the two stones are to hit

the water simultaneously?

magnitude m/s

direction

(c) What is the speed of each stone at the instant the two stones hit the water?

first stone m/s

second stone m/s

 
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Phyiscs Lab Simulation

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More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird.

Name _________________________________ Section ______________ Date ______________

CONCEPTUAL PHYSICS Tech Lab Electromagnetic Induction: Generators and Alternating Current Electromagnetism Sim

Faraday’s Electromagnetic Lab Purpose To manipulate simulated magnets, compasses, and coils to see how magnetic fields interact with electric currents

Apparatus computer PhET sim, “Faraday’s Electromagnetic Lab” (available at http://phet.colorado.edu)

Discussion When Hans Christian Ørsted discovered that electricity could be used to produce magnetism, the scientific community anticipated that it wouldn’t be long before someone would discover how magnetism could be used to produce electricity. But more than ten years would pass before Michael Faraday solved the puzzle.

The application of engineering to electromagnetism led to motors and generators. Nearly any electrical device that produces motion uses a motor. Any device that is plugged into a wall outlet draws power from a generator. Our reliance on applications of electromagnetism is never more apparent than during a power outage.

The interactions between electricity and magnetism are not always easy to grasp. In this activity, you will manipulate elements in a simulated laboratory and get visual feedback.

Procedure PART A: BAR MAGNET Step 1: Run the PhET sim, “Faraday’s Electromagnetic Lab.” It should open to the Bar Magnet tab. Maximize the window. You should see a bar magnet, a compass, and a compass needle grid.

Step 2: Center the bar magnet horizontally on the fourth or fifth row from the top. Set the large compass just below the bar magnet at its midpoint. It’s okay for the two objects to be touching. See Figure 1.

Step 3: If the compass needles (in the grid or in the large compass) are to be thought of as arrows indicating the direction of the bar magnet’s magnetic field, each one should be visualized as pointing

__“redward” __“whiteward”. Figure 1.

More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird.

Step 4: Using the on-screen slider in the control panel, run the strength of the bar magnet up and down. How does the sim show the difference between a strong magnet and a weak magnet?

Step 5: How does the strength of the magnetic field change with increasing distance from the bar magnet and how does the sim show this?

Step 6: With the magnet at its strongest, reverse it’s polarity using the on-screen “Flip Polarity” button in the control panel. What are the ways in which the sim reflects this polarity reversal?

Step 7: Describe the behavior of the compass during a polarity reversal (magnet initially at 100%) a. when the compass is touching the bar magnet at its midpoint.

b. when the compass is far from the bar magnet (touching the bottom of the sim window), but still on a perpendicular bisector of the bar magnet.

c. when the compass is far from the bar magnet and the magnet’s strength is set to 10%.

Step 8: a. Around the exterior of the bar magnet, the direction of the magnetic field is from its ____ pole to its ____ pole.

b. What is the direction of the magnetic field in the interior of the bar magnet? And how did you find out?

More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird.

PART B: ELECTROMAGNET Step 1: Run the PhET sim, “Faraday’s Electromagnetic Lab.” Maximize the window. Click the on- screen Electromagnet tab. Arrange the on-screen elements so that the top of the battery is along the second or third row of the compass grid. Notice that the magnetic field around the coil is very similar to the magnetic field around the bar magnet.

Step 2: There is no “Strength %” slider on the control panel. a. How can you change the strength of the electromagnet?

b. In real life, is it easier to change the strength of a bar magnet or an electromagnet?

Step 3: There is no “Flip Polarity” button on the control panel. How can you reverse the polarity of the electromagnet?

Step 4: In the control panel, switch the Current Source from the battery (DC: direct current) to an oscillator (AC: alternating current). If necessary, move the electromagnet so that you can see the entire oscillator.

a. What does the vertical slider on the AC source do?

b. What does the horizontal slider on the AC source do?

Step 5: What should the sliders be set to in order to create a “dance party” display? Can you make the dance party even more annoying using the Options menu? Describe.

More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird.

PART C: PICKUP COIL Step 1: Run the PhET sim, “Faraday’s Electromagnetic Lab.” Maximize the window. Click the Pickup Coil tab. You should see a bar magnet, a compass needle grid, and a coil attached to a light bulb.

Step 2: Describe the most effective way of using the magnet and the coil to light the bulb if

a. the coil cannot be moved.

b. the magnet cannot be moved.

Step 3: Rank the arrangements and motions shown below from most effective to least effective in terms of lighting the bulb, allowing for ties. For example, if A were most effective, B were least effective, and C and D were equivalent to one another, the ranking would be A > C = D > B.

A. Transverse External

B. Transverse Internal

C. Longitudinal Internal

D. Longitudinal External

Step 4: Move the bar magnet through the coil and observe the motion of the electrons in the forward arc of the coil loops. Report the correlations of magnet motion and electron motion.

a. Magnet approaches from the left, north pole first; electrons move downward.

b. Magnet departs to the right, south end last; electrons move upward.

c. Magnet approaches from the right, south pole first; electrons move _?_.

d. Magnet departs to the left, north end last; electrons move _?_.

More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird.

e. Magnet approaches from the left, south pole first; electrons move _?_.

f. Magnet departs to the right, north end last; electrons move _?_.

g. Magnet approaches from the right, north pole first; electrons move _?_.

h. Magnet departs to the left, south end last; electrons move _?_.

PART D: TRANSFORMER 1. Run the PhET sim, “Faraday’s Electromagnetic Lab.” Maximize the window. Click the on-screen Transformer tab. You should see an electromagnet and a pickup coil.

2. Experiment with the various control panel settings and the positions of the electromagnet and the pickup coil to determine a method for getting the most light out of the bulb. Describe the settings and locations.

More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird.

PART E: GENERATOR 1. Run the PhET sim, “Faraday’s Electromagnetic Lab.” Maximize the window. Click the on-screen Generator tab. You should see a faucet, paddlewheel with bar magnet, compass, and a pickup coil.

2. Experiment with the various settings to determine a method for getting the most light out of the bulb. Describe the settings.

3. What is the story of light production here? Organize and connect the given “plot elements” and add any key elements that were omitted from the list to construct the complete story.

• light radiated from the bulb

• changing magnetic field

• induced electric current

• motion of the bar magnet

• kinetic energy of the water • heat the filament

 
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Physics

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1- Below is an image of a bar magnet with its poles indicated.  Imagine a compass being placed at position X and then at position Y.  Which direction would the North Pole of the compass point at each position?

Select one:

a. The North Pole of the compass would point to the right at position X and to the right at position Y.

b. The North Pole of the compass would point to the right at position X and to the left at position Y.

c. The North Pole of the compass would point to the left at position X and to the left at position Y.

d. The North Pole of the compass would point to the left at position X and to the right at position Y.

————————————————————–

2- Below are images of three positions of a compass near a bar magnet.  The pointed end of the compass needle represents its North Pole.  Only one of these three images shows the correct orientation of the compass needle, the other two are incorrect.  Which image is correct?

Select one:

a. Image A

b. Image C

c. Image B

—————————————————————-3-Which of the following statements best explains why the North Pole of a compass needle points (approximately) toward the geographic North Pole of the Earth?

Select one:

a. The South Pole of the imaginary large bar magnet inside the Earth lies close to the geographic North Pole.

b. The North Pole of the imaginary large bar magnet inside the Earth lies close to the geographic North Pole.

—————————————————————-

4- which of the following materials can interact with (be affected by) a magnet?

Select one:

a. All of them

b. Aluminum

c. Brass

d. Steel

e. Copper

5- Consider the model from a different group, similar to but not the same as Group 2’s model:

Description: There are no magnetic entities associated with the unmagnetized nail, but when a magnet is rubbed along the surface of the nail, it deposits small N and S entities (like dust particles) loosely along the surface, as shown.

Which of the following observations made by some other groups would be difficult to explain (or could not be explained) using this model? (Choose all that apply.)

Select one or more:

a. Cutting the nail anywhere along its length produces two pieces that each behave like two-ended magnets.

b. The magnetized nail behaves like a two-ended (bar) magnet.

c. When cut in half, each end of each half of the nail (four ends in all) can pick up the same number of paper clips.

d. Cutting the magnetized nail in half produces two pieces that each behave like two-ended magnets.

e. After dropping the magnetized nail in water and removing it, the wet nail is still magnetized.

f. Each end of the magnetized nail can pick up the same number of paper clips.

—————————————————————-

6- Now consider a group who found that, when they cut a magnetized nail into either halves or ¼ and ¾ pieces, the pieces of the magnetized nail still behaved as if they were two-ended.

Description: Inside the nail, there are equal numbers of separate N and S magnetic particles that can move around when attracted or repelled by a magnet. In the unmagnetized nail, they are all jumbled up randomly. When the nail is rubbed with one pole of a bar magnet, the magnetic particles arrange themselves as shown in the diagram.

Which of the following observations made by some other groups would be difficult to explain using this model? (Choose all that apply.)

Select one or more:

a. After dropping the magnetized nail in water and removing it, the wet nail is still magnetized.

b. The magnetized nail behaves like a two-ended (bar) magnet.

c. Each end of the magnetized nail can pick up the same number of paper clips.

d. When cut in half, each end of each half of the nail (four ends in all) can pick up the same number of paper clips.

e. Cutting the nail anywhere along its length produces two pieces that each behave like two-ended magnets.

—————————————————————-

7- This group’s model is similar to the last group’s model. In this case, the group performed experiments in which they cut a number of magnetized nails into two pieces of various lengths and found that both pieces were always two-ended. Here is their model for the magnetized nail:

Description: Inside the nail there are equal numbers of separate N and S magnetic particles that can move around when attracted or repelled by a magnet. In the unmagnetized nail, these N and S particles are all jumbled up randomly. When the nail is rubbed with one pole of a bar magnet, the magnetic particles arrange themselves alternately along the length of the nail.

Could this model be used to explain the observation that when a magnetized nail is cut into two pieces of arbitrary lengths both pieces are always two-ended?

Select one:

a. Yes, according to the model diagram, anywhere the nail is cut would produce two pieces that are both two-ended.

b. No, according to the diagram, there are some places where the nail could be cut and the two pieces produced would not be two-ended.

—————————————————————-

8- Here are four possible things that could be done to any object.

I.Hit it with another hard object.

II.Heat it to a very high temperature.

III.Cool it to a very low temperature.

IV.Bring it close to one end of a permanent magnet.

Considering all the evidence you have seen in this unit, in terms of the alignment of domains model, which of these seem to be able to change the orientation of at least some of the domains in a ferromagnetic object?

Select one:

a. I, II, III, and IV

b. II and III

c. I, II, and III

d. I and II

e. I, II, and IV

—————————————————————-

9- A group of students constructed the following explanation for why the N-pole of compass needle rotated toward the tip of a magnetized nail placed at the E-label, but after the nail was heated the needle showed no reaction.

(1) Before it is heated all the S-poles of the domains in the magnetized nail are facing the tip of the nail, making it a S-pole that attracts the N-pole of the compass needle. (2) When the nail is heated the domains get jumbled up with no preferred direction of alignment. This means the tip of the nail is now unmagnetized and the tip is longer any particular pole. (3) Since there is an attraction between an unmagnetized object and both poles of a magnet, both ends of the compass needle are now attracted to the nail. These two attractions tend to make the needle rotate in opposite directions, so they cancel each other out and the needle does not move.

What is your evaluation of this explanation in terms of whether it is well constructed or not?

Select one:

a. It is well-constructed.

b. It is not well constructed because it is not relevant.

c. It is not well constructed because the diagram is not clear or the narrative is not easy to read.

d. It is not well-constructed because the diagram and narrative are inconsistent.

—————————————————————-

10- Now consider only the narrative from the same explanation

(1) Before it is heated all the S-poles of the domains in the magnetized nail are facing the tip of the nail, making it a S-pole that attracts the N-pole of the compass needle. (2) When the nail is heated the domains get jumbled up with no preferred direction of alignment. This means the tip of the nail is now unmagnetized and the tip is longer any particular pole. (3) Since there is an attraction between an unmagnetized object and both poles of a magnet, both ends of the compass needle are now attracted to the nail. These two attractions tend to make the needle rotate in opposite directions, so they cancel each other out and the needle does not move.

What is your evaluation of this narrative in terms of whether it is accurate or not?

Select one:

a. It is accurate.

b. It is not accurate because part (2) is not consistent with the class consensus model.

c. It is not accurate because part (3) is not consistent with how we know unmagnetized and magnetized objects interact with each other.

d. It is not accurate because part (1) is not consistent with the class consensus model and/or the Law of Magnetic Poles.

—————————————————————-

11- Again, consider only the narrative from the same explanation

(1) Before it is heated all the S-poles of the domains in the magnetized nail are facing the tip of the nail, making it a S-pole that attracts the N-pole of the compass needle. (2) When the nail is heated the domains get jumbled up with no preferred direction of alignment. This means the tip of the nail is now unmagnetized and the tip is longer any particular pole. (3) Since there is an attraction between an unmagnetized object and both poles of a magnet, both ends of the compass needle are now attracted to the nail. These two attractions tend to make the needle rotate in opposite directions, so they cancel each other out and the needle does not move.

What is your evaluation of this narrative in terms of whether it is well-reasoned or not?

Select one:

a. It is not well reasoned because it does not explain why the compass needle is attracted to the nail before heating.

b. It is not well-reasoned because it does not explain why the compass needle does not react to the the nail after it was heated.

c. It is not well-reasoned because it does not explain why heating the nail causes the domains to change their orientation.

d. It is well-reasoned.

 
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Physic Questions

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Home>Homework Answsers>Physics homework help

9. An 10.0 g bullet, moving at 200 m/s, goes through a stationary block of wood in 3.0x10–4 s, emerging at a speed of 200 m/s.

(a) What average force did the wood exert on the bullet?

(b) How thick is the wood?

10. An artificial Earth satellite, of mass 3.00 * 103 kg, has an elliptical orbit, with a mean altitude of 500 km.

(a) What is its mean value of gravitational potential energy while in orbit?

(b) What is its mean value of orbital kinetic energy?

(c) What is its total energy while in orbit?

(d) If its perigee is 150 km, what is its orbital velocity at perigee?

Q3 A positive charge of 3.2 x 10-5 C experiences a force of 4.8n to the right when placed in an electric field. What is the magnitude and direction of the electric field at the location of the charge?

Q4 What is the gravitational field intensity at the surface of Mars if a 2.0kg object experiences a gravitational force of 7.5 N?

Q6 What is the gravitational field intensity at a distance of 8.4 x 107 m from the centre of Earth?

Q7 Find the electric potential energy stored between charges of +2.6 μC and -3.2 μC placed 1.6m apart

Q9 A pair of metal plates, mounted 1.0cm apart on insulators, is charged oppositely. A test charge of +2.0 μC placed at the midpoint, M, between the plates experiences a force of 6.0 x 10-4 N [W]

a. what is the electric field intensity at M?

b. what is the electric field intensity at a point 2.0mm from negative plate?

c. what is the electric field intensity at a point 1.0mm from the positive plate?

d. what are two possible ways in which you could double the strength of the electric field?

Q10 When an 80.0 V battery is connected across a pair of parallel plates, the electric field intensity between the plates is 360.0N/C.

a. What is the distance of separation of the plates?

b. What force will be experienced by a charge of -4.0 μC placed at the midpoint between the plates?

c. Calculate the force experienced by the charge in part (b) if it is located one quarter of the way from positive plate.

Q11 Two large horizontal parallel plates are separated by 2.00cm. an oil drop, mass 4.02 x 10-15kg, is held balanced between the plates when a potential difference of 820.0V is applied across the plates, with the upper plate being negative

a. what is the charge on the drop?

b. what is the number of excess or deficit electrons on the oil drop?

Q12 A proton is projected into magnetic field of 0.5T directed into the page. If the proton is travelling at 3.4 x 105 m/s in a direction [up 28o right], what is the magnitude and direction of the magnetic force on the proton?

6. A 2.4 ´ 10–3-C positive test charge is placed between two plates. The potential difference between two parallel metal plates is 30 V. Plate A is positive and plate B is negative. Which plate has a higher electric potential?

a. plate A
b. plate B
c. Plates A and B have the same potential.
d. If the positive charge is placed closer to the positive plate, then plate A will have a greater electric potential.
e. If the positive charge is placed closer to the negative plate, then plate B will have a greater electric potential.

 

 

8. a. Calculate the electric field 2.0 m from a small sphere with a positive charge of 2.3 ´ 10–3 C.

b. Charged spheres X and Y are in a set position and have charges  and , respectively. Calculate the net force on sphere Z, of charge .

 

Q1 Determine the distance that the third bright fringe would lie from the central bisector in a single slit diffraction pattern generated with 542 nm light incident on a 1.2 x 10-4 m slit falling onto a screen 68cm away.

Q2 A special effects creator wants to generate an interference pattern on a screen 6.8m away fro a single slit. She uses 445 nm light and hopes to get the second dark fringe exactly 48 cm from the middle of the central bright maximum. What width of the slit does she require?

Q3 What is the speed of light in water if, in water,

ε = 7.10 x 10-10 C2/N.m2 and μ = 2.77 x 10-8 N/A2.

Q4 a. Determine the wavelength of an AM radio signal with a frequency of 6.40 x 106 Hz.

b. Suggest why AM radio transmitting antennas are hundreds of meters tall.

Q2. An asteroid has a long axis of 725km. A rocket passes by a parallel to the long axis at a speed of 0.250c. What will be the length of the long axis as measured by the observers in the rocket?

An electron is moving at 0.95c parallel to a meter stick. How long will the meter stick be in the electron’s frame of reference?

A neutron is measured to have a mass of 1.71 x 10-27kg when travelling at 6.00 x 107 m/s. Determine its rest mass

Find the wavelength of a jet airplane with a mass of 1.12 x 105 kg that is cruising at 891km/h.

If the work function of the material is 2.0 ev and the light of the wavelength 500nm is shone on the metal, find the kinetic energy of the electron

Alpha centuari, the closest star to earth, is 4.3* 10^16 m away. How long would it take a spaceship to reach the star if were traveling at 0.999c.

A 1.0m long object with a rest mass of 1.0 kg is moving at 0.90c.find its relativistic length and mass.

A particle travels at 0.80c. if its rest mass is 2.58* 10^-28 kg, what is its relativistic kinetic energy compared to its classical kinetic energy.

1. Kyle is in his car traveling at a constant speed of 150 km/h down the road. He passes a police car that was stationary at the side of the road. He sees the radar reading and immediately begins accelerating (8 m/s/s) in order to catch the delinquent teenager. How long and how far down the road does he catch Kyle?

2. After landing safely on the target the cat tries another projectile apparatus. This time the cat is shot out of a cannon over a 30 m high wall. The cat is launched at an angle of 55º0 and can be assumed to be at ground level during launch. With what speed (in km/h) does it have to be launched to make it approximately 5 m over the wall if the wall is 250 m from the cannon?

3. Box A (m=2.5 kg) is connected by a rope that passes over a frictionless pulley to Box B (m=5.5 kg), as shown in figure. The coefficient of kinetic friction between box and ramp is 0.54. Determine the acceleration of the boxes.

. 

4. A 1.2×103 kg space probe, travelling initially at a speed of 9.5×103 m/s through deep space, fires its engines that produce a force of magnitude 9.2×104 N over a distance of 86 km. Determine the final speed of the probe.

6. An α particle of charge +3.2×10-19 C and mass 6.7×10-27 kg first accelerates through a potential difference of 1.2×103 V, then enters a uniform magnetic field of magnitude 0.25 T at 90º. Calculate the magnetic force on the particle.

8. Two sources are vibrating in phase, and set up waves in a ripple tank. A point P on the second nodal line is 12.0 cm from source A and 20.0 cm from source B. When the sources are started, it takes 2.0 s for the first wave to reach the edge of the tank, 30 cm from the source. Find the velocity, wavelength and frequency of the wave.

 
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Physics Lab Report

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I need someone do my physics lab reports.

Expression of the experimental results is an integral part of science. The lab report should have the following format:

 Cover page (10 points) – course name (PHY 132), title of the experiment, your name (prominent), section number, TA’s name, date of experiment, an abstract. An abstract (two paragraphs long) is the place where you briefly summarize the experiment and cite your main experimental results along with any associated errors and units. Write the abstract after all the other sections are completed.

The main body of the report will contain the following sections, each of which must be clearly labeled:

  • Objectives (5 points) – in one or two sentences describe the purpose of the lab. What physical quantities are you measuring? What physical principles/laws are you investigating?
  • Procedure (5 points) – this section should contain a brief description of the main steps and the significant details of the experiment.
  • Experimental data (15 points) – your data should be tabulated neatly in this section. Your tables should have clear headings and contain units. All the clearly labeled plots (Figure 1, etc.) produced during lab must be attached to the report. The scales on the figures should be chosen appropriately so that the data to be presented will cover most part of the graph paper.
  • Results (20 points) – you are required to show sample calculation of the quantities you are looking for including formulas and all derived equations used in your calculations. Provide all intermediate quantities. Show the calculation of the uncertainties using the rules of the error propagation. You may choose to type these calculations, but neatly hand write will be acceptable. Please label this page Sample Calculations and box your results. Your data sheets that contain measurements generated during the lab are not the results of the lab.
  • Discussion and analysis (25 points) – here you analyze the data, briefly summarize the basic idea of the experiment, and describe the measurements you made. State the key results with uncertainties and units. Interpret your graphs and discuss what trends were observed, what was the relationship of the variables in your experiment. An important part of any experimental result is a quantification of error in the result.  Describe what you learned from your results. The answers to any questions posed to you in the lab packet should be answered here.
  • Conclusion (5 points) – Did you meet the stated objective of the lab? You will need to supply reasoning in your answers to these questions.

Overall, the lab report should to be about 5 pages long.

Each student should write his/her own laboratory report.

Duplicating reports will result in an “E” in your final grade.

All data sheets and computer printouts generated during the lab have to be labeled Fig.1, Fig. 2, and included at the end of the lab report.

Lab report without attached data sheets and/or graphs generated in the lab will automatically get a zero score.

 
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Phy191 Exam

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Rotational Energy & Static Equilibrium

3/30/2108

1

A Summary So Far

Kinematics:

Dynamics:

Energy:

Momentum:

2

Constant Acceleration

Rotational Kinetic Energy

Consider our old pal the uneven dumbbell…

What kinetic energy does the system have?

So, rotational kinetic energy must then be:

3

Energy of a Rigid Body

The energy for a cluster of masses can be generalized to a continuous object:

4

Axis of Rotation

Whiteboard Problem 12-12

A 300g ball and a 600g ball are connected by a 40cm long massless, rigid rod to form a dumbbell. The dumbbell rotates around its center of mass at 100rpm.

What is the rotational kinetic energy of the dumbbell? (LC)

5

Static Equilibrium

For objects that aren’t points, equilibrium is a bit different.

This is a future you problem.

15

FBD:

x

y

Previously in PHY191…

6_2, slide 15

6

Static Equilibrium

A body is in static equilibrium if:

Torque about any point must be zero.

Side note: forces acting at a pivot point produce 0 torque.

7

A note on Gravity

Gravity can exert a force, but what about a torque?

Gravity acts over the entire body.

Whenever you’re solving a problem, know that gravity will effectively act at the center of gravity of an object.

This is the same location as the center of mass for all of the objects we will consider in this class.

8

Solving Static Equilibrium Problems

Picture

Reference Frame

Including rotation direction (CCW +)

Draw a FBD

Sum the forces in all directions

They sum to zero

Sum the torques about a point (usually a pivot)

They sum to zero

Solve

9

A beam of mass M and length L is resting on a pivot as shown below:

What must the force F be in order to keep the beam still?

Example

10

Whiteboard Problem 12-10

The two blocks of citrine shown below have uniform density and are balanced on the pivot.

Draw Free Body Diagrams for both blocks. What is the force of the upper block on the lower block?

Use the FBD of the lower block to find the distance d. (LC)

11

That’s about 15,000$ of citrine.

11

Whiteboard Problem 12-11

In the figure below, an 80kg construction worker sits down 2.0m from the end of a 1450kg steel beam to eat his lunch. The cable supporting the beam can withstand a maximum tension of 15,000N.

Draw a FBD of the beam.

Determine the tension in the cable (LC) – does the cable break?

12

Live Action Science

What is the mass of a meter stick?

On Canvas, find the assignment labeled Meter stick mass, make a copy of the google document and share it with your group.

Using the materials on the wire rack on the East side of the room, determine a method using what we’ve learned so far this week to determine the mass of a meter stick. Record your process on the google doc.

13

 
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DC Circuit Lab Report

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Report for Experiment 4

Newton’s Second Law

Name: Your name here

Lab partner: Your partner’s name here

TA: Your instructor’s name here

The date of the experiment here

Abstract

Acceleration is the coupling strength between the mass of a system and the force acting on it. By

comparing the gravitational pull on a . One hanging mass of variable weight is attached to either one

puck (Investigation 1) or two (Investigation 2) on a frictionless air table. A spark timer gives a direct way

to measure velocity and time of the system, calculating acceleration for three hanging weights. Plotting

acceleration vs. the reduced mass of the hanging weights gives a value for gravity. Using one puck, the

data within uncertainty is equal to the standard value of gravity. Using two pucks, the data was not equal

to gravity within error, as rotational and frictional forces were not included in the linear model.

Introduction

This experiment will test Newton’s second law and how it relates to different forces. The law can be

summarized by the equation, F = ma. It is the point of this experiment to find an acceleration of an object

based on a given force and mass of that object. This will effectively solve Newton’s second law in the

form a = F/m. In the first investigation we measured the displacement of an air hockey puck as it was

pulled by three differing weights, using a spark timer. We calculated the velocity of the puck and graphed

velocity vs. time for each weight combination, which gave the acceleration of the puck. To verify

Newton’s second law we graphed the accelerations vs. the reduced mass of the system and then compared

the slope of that graph to the known value of gravity, 9.81 m/s^2. The second investigation used two

pucks strapped together, thereby changing the reduced mass ratio, but otherwise worked the same way as

Investigation 1 to calculate the known value of gravity.

Investigation 1

Setup & Procedure

The air table is set up with a pulley attached to a side. Two pucks are connected to a High Voltage (HV)

source to create a circuit for the spark timer. Carbon paper is laid on the table with white paper laying on

top of this carbon paper. The second puck is to the side but still on the paper so as not to interfere with

the motion of the puck under observation. Weights of either 50, 100, or 200 grams is attached to the puck

by the pulley and string. When the HV is on, the weight is dropped and the puck generates a spark every

30 ms. The spark will leave a black carbon dot from the carbon paper on the white paper, which can be

measured for displacement. The spark timer is set to 30 Hz, so the time between each dot is 0.0333 s.

Ten dots are counted and the displacement between them measured. Using this data, the velocity is

calculated and used to graphically find the acceleration of the system.

Data & Analysis

Table 1 – Displacement and time data from a single puck with different weights

hanging down. (a) Data from the 50g hanging weight; (b) Data from the 100g

hanging weight; (c) Data from the 200g hanging weight.

hanging weight 50 g

puck (g) 548

displacement # Δx (cm) Δt (s) t (s) δΔx (cm) v (cm/s) δv (cm/s)

1 1.9 0.0333 0.033 0.3 28.528 4.504

2 2 0.0333 0.066 0.3 30.030 4.504

3 2.1 0.0333 0.1 0.3 31.531 4.504

4 2.2 0.0333 0.133 0.3 33.033 4.504

5 2.4 0.0333 0.166 0.3 36.036 4.504

6 2.5 0.0333 0.2 0.3 37.537 4.504

7 2.6 0.0333 0.233 0.3 39.039 4.504

8 2.8 0.0333 0.266 0.3 42.042 4.504

9 2.9 0.0333 0.3 0.3 43.543 4.504

hanging weight 100 g

puck (g) 548

displacement # Δx (cm) Δt (s) t (s) δΔx (cm) v (cm/s) δv (cm/s)

1 2.3 0.0333 0.033 0.3 34.534 4.504

2 2.5 0.0333 0.066 0.3 37.537 4.504

3 2.8 0.0333 0.1 0.3 42.042 4.504

4 3.1 0.0333 0.133 0.3 46.546 4.504

5 3.5 0.0333 0.166 0.3 52.552 4.504

6 3.6 0.0333 0.2 0.3 54.054 4.504

7 3.8 0.0333 0.233 0.3 57.057 4.504

8 4.2 0.0333 0.266 0.3 63.063 4.504

9 4.5 0.0333 0.3 0.3 67.567 4.504

hanging weight 200 g

puck (g) 548

displacement # Δx (cm) Δt (s) t (s) δΔx (cm) v (cm/s) δv (cm/s)

1 2.1 0.0333 0.033 0.3 31.531 4.504

2 2.7 0.0333 0.066 0.3 40.540 4.504

3 3.2 0.0333 0.1 0.3 48.048 4.504

4 3.5 0.0333 0.133 0.3 52.552 4.504

5 4 0.0333 0.166 0.3 60.060 4.504

6 4.4 0.0333 0.2 0.3 66.066 4.504

7 5 0.0333 0.233 0.3 75.075 4.504

8 5.6 0.0333 0.266 0.3 84.084 4.504

9 5.9 0.0333 0.3 0.3 88.588 4.504

On the paper, each trail of dots was labeled for the specific weight used on the pulley. Our TA helped

pick a starting dot, and the dots were numbered 1-10. We measured the displacement between two

consecutive dots and labeled it Δx. For example, for displacement #1, we measured the distance between

dots 1 and 3. For displacement #2 we measured the distance between dots 2 and 4, etc. The next column

in the data, Δt (s), is the time between each carbon dot. The column after that is the total time elapsed

from the first dot. The uncertainty of the displacement was determined by the difficulty to accurately

measure the middle of the dot, the size of the dot, and the fact that the ruler could not touch the paper

directly. The relative uncertainty of the time measurement has been pre-determined to be 0.1%. This is

effectively negligible in comparison to the uncertainty of the physical measurements.

The velocity of the puck was calculated using the equation 𝑣 = Δ𝑥/(2Δ𝑡). The uncertainty to the

velocity was calculated in Eq. (1),

δv = δ∆𝑥

∆𝑥 × v (1)

From this, we created a graph of velocity vs. time for each weight, seen in Fig. (1). Error bars and an

equation of the trend line were added. We imputed the data into the IPL error calculator and found an

uncertainty of the slope of 17.4 cm/s^2 for each graph.

Figure 1 – Acceleration from pucks using different weights. (a) Puck acceleration from hanging 50g weight;

(b) Puck acceleration from hanging 100g weight; (c) Puck acceleration from hanging 200g weight.

y = 57.808x + 26.068

0

10

20

30

40

50

60

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

V e

lo ci

ty (

cm /s

)

Time (s)

y = 123.12x + 30.03

0

10

20

30

40

50

60

70

80

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

V e

lo ci

ty (

cm /s

)

Time (s)

y = 213.21x + 25.192

0

10

20

30

40

50

60

70

80

90

100

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

V e

lo ci

ty (

cm /s

)

Time (s)

The slope of each graph is the acceleration of the puck. Newton’s second law states that the sum of all

forces equals mass times acceleration. Since gravity acting on the weight is the only force acting on the

puck (as long as friction is negligent), then Newton’s law can be written as

𝑚𝑤𝑔 = (𝑚𝑝 + 𝑚𝑤)𝑎, (2)

where mp is the mass of the puck, mw is the mass of the weight, a is the acceleration, and g is gravity. If

acceleration is graphed against mw/(mp+mw), then the slope of the line will be equal to the acceleration of

gravity. This is done in Fig. (2).

Table 2 – Reduced mass and acceleration data.

Weight added (g)

Reduced mass

mw/(mp+mw) a (cm/s^2) δa (cm/s^2)

50 0.154 57.8 17.4

100 0.214 123.1 17.4

200 0.313 213.2 17.4

Figure 2 – Average gravitational acceleration of the three trials.

The slope of our graph is 971.64 cm/s^2. We used the IPL calculator to get the uncertainty of our

calculated gravity, 153.36 cm/s^2. This means our value of gravity 971.64 cm ±153.36 cm is equal to

9.81m/s^2, so Newton’s second law is verified.

Investigation 2

Setup & Procedure

We used the same set up as Investigation 1, but instead of one puck we used both pucks Velcroed

together. All setup, procedures, equations, and graphs were the same as before.

y = 971.64x – 89.683

0

50

100

150

200

250

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

A cc

e le

ra ti

o n

( cm

/s ^

2 )

Reduced mass

Table 3 – Displacement and time data from two pucks with different weights

hanging down. (a) Data from the 50g hanging weight; (b) Data from the 100g

hanging weight; (c) Data from the 200g hanging weight.

hanging weight 50 g

puck (g) 1096

displacement # Δx (cm) Δt (s) t (s) δΔx (cm) v (cm/s) δv (cm/s)

1 2 0.0333 0.033 0.3 30.030 4.504

2 2.1 0.0333 0.066 0.3 31.531 4.504

3 2.2 0.0333 0.1 0.3 33.033 4.504

4 2.3 0.0333 0.133 0.3 34.534 4.504

5 2.4 0.0333 0.166 0.3 36.036 4.504

6 2.5 0.0333 0.2 0.3 37.537 4.504

7 2.4 0.0333 0.233 0.3 36.036 4.504

8 2.5 0.0333 0.266 0.3 37.537 4.504

9 2.7 0.0333 0.3 0.3 40.540 4.504

 

hanging weight 100 g

puck (g) 1096

displacement # Δx (cm) Δt (s) t (s) δΔx (cm) v (cm/s) δv (cm/s)

1 1.5 0.0333 0.033 0.3 22.522 4.504

2 1.7 0.0333 0.066 0.3 25.525 4.504

3 1.8 0.0333 0.1 0.3 27.027 4.504

4 2.1 0.0333 0.133 0.3 31.531 4.504

5 2.2 0.0333 0.166 0.3 33.033 4.504

6 2.4 0.0333 0.2 0.3 36.036 4.504

7 2.6 0.0333 0.233 0.3 39.039 4.504

8 2.6 0.0333 0.266 0.3 39.039 4.504

9 2.7 0.0333 0.3 0.3 40.540 4.504

 

hanging weight 200 g

puck (g) 1096

displacement # Δx (cm) Δt (s) t (s) δΔx (cm) v (cm/s) δv (cm/s)

1 3.6 0.0333 0.033 0.3 54.054 4.504

2 3.7 0.0333 0.066 0.3 55.555 4.504

3 4 0.0333 0.1 0.3 60.060 4.504

4 4.2 0.0333 0.133 0.3 63.063 4.504

5 4.4 0.0333 0.166 0.3 66.066 4.504

6 4.7 0.0333 0.2 0.3 70.570 4.504

7 4.8 0.0333 0.233 0.3 72.072 4.504

8 5.1 0.0333 0.266 0.3 76.576 4.504

9 5.3 0.0333 0.3 0.3 79.579 4.504

We use the same equations for calculation of velocity and uncertainty as Investigation 1. Velocity vs.

time was graphed for each of the three weights used, as seen in Fig. (3).

Figure 3 – Acceleration from pucks using different weights. (a) Puck acceleration from hanging 50g weight;

(b) Puck acceleration from hanging 100g weight; (c) Puck acceleration from hanging 200g weight.

Since the uncertainty of velocity did not change at all, the uncertainty for each slope is still 17.4 cm/s^2.

The acceleration of the pucks was again graphed against mw/(mp+mw) and error bars and an equation of

the trend line were added.

 

y = 34.535x + 29.446

0

5

10

15

20

25

30

35

40

45

50

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

V e

lo ci

ty (

cm /s

)

Time (s)

y = 70.571x + 20.938

0

10

20

30

40

50

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

V e

lo ci

ty (

cm /s

)

Time (s)

y = 98.348x + 50.008

0

10

20

30

40

50

60

70

80

90

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

V e

lo ci

ty (

cm /s

)

Time (s)

Table 4 – Reduced mass and acceleration data for the double puck configuration.

Weight added (g)

Reduced mass

mw/(mp+mw) a (cm/s^2) δa (cm/s^2)

50 0.084 34.5 17.4

100 0.120 70.6 17.4

200 0.186 98.3 17.4

Figure 4 – Average gravitational acceleration of the three trials using two pucks.

Since uncertainties did not change, the uncertainty to Fig. (4) is again 153.36 cm/s^2. Our graph shows

that our value for gravity of 601.37 ± 153.36 cm/s^2 is not equal to 9.81 m/s^2. There are many reasons

why our value is not equal. It could be off because of the pucks turned while they were pulled down the

table, which would change some of the linear force into rotational force and thus reduce acceleration.

Also, the pucks weren’t secured very well with the string and Velcro tied to it, so that one puck always

lurched forward instead of both pucks traveling together smoothly. This would greatly affect the spacing

of the spark data points on the table. There may have also been enough friction on the string against the

pulley to affect the acceleration of the system.

Conclusion

In our first investigation we measured gravity as 971.64 ± 153.36 cm/s^2, which is equal the given value

of 9.81m/s^2. But in our second investigation our gravity of 601.37 ± 153.36 cm/s^2 is not equal to 9.81

m/s^2. Extra forces that we didn’t account for, or rotational effects, could have decreased the acceleration

of the pucks. Newton’s second law tells us no matter the amount of weight our gravity should still equal

9.81m/s^2, but that was not the case in our second investigation. A different method of tying and

Velcroing the two pucks together might alleviate the rotational effects if the experiment was performed

over again.

y = 601.37x – 10.324

0

20

40

60

80

100

120

140

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2

A cc

e le

ra ti

o n

( cm

/s ^

2 )

Reduced mass

Questions

1. In each investigation, you measure mass and acceleration. Which measurement has the greater

percent error? Don’t just say yes or no. Be quantitative in your answer.

The answer to Question 1 goes here, including all relevant calculations.

2. Assume that the spark timer error is 1%. Can it be neglected compared to the error in x?

Explain!

The answer to Question 2 goes here, including all relevant calculations.

3. What is the acceleration of the system if the hanging mass is doubled and the puck’s mass is

doubled?

The answer to Question 3 goes here, including all relevant calculations.

4. What is the acceleration if the hanging mass is doubled and the puck’s mass is halved?

The answer to Question 4 goes here, including all relevant calculations.

Acknowledgements

This experiment would not have been possible without the help of my lab partner, Kevin. I’d also

like to thank my TA, Andrew Taylor, for the valuable help in understanding how to calculate uncertainty

for both velocity and acceleration.

References

[1] H.Young and R.Freedman, University Physics, 13th edition, Pearson Education.

[2] O.Batishchev and A.Hyde, Introductory Physics Laboratory, pp 31-36, Hayden-McNeil, 2015.

 
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Ball Toss Report

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Grading Rubric:

Format of report is worth 1 point

Objectives are worth 2 points

Preliminary Questions are 1 point each, for a total of 3 points

Method is worth 2 points

Data is worth 3 points. You need the Data Table as well as the plots of position, velocity, and acceleration vs. time

Data Analysis is worth 3 points

Questions are 1 point per question, but for this assignment, Question 1 has 7 parts, worth total of 7 points, total overall of 16 points for questions

Conclusions are worth 3 points. The conclusions normally describe what you learned in the lab, and if it succeeded. Start by looking at the objectives of the lab. Were they satisfied? If they were, in the conclusions, state something like: In the ball toss lab, a basketball was tossed above a motion detector, and displacement, velocity, and acceleration were plotted vs. time. Each plot was studied. For the free fall section of each plot, a best fit curve, line, or statistics were used. A quadratic curve fit for the displacement plot, a linear curve fit for the velocity plot, and mean was used for the acceleration plot. Each fit was used to compare with the acceleration of gravity, and each parameter fit within a few percent error of the acceleration of gravity.

You can make it less technical, or longer or shorter.

The “Lab 4 Ball Toss ON 2 Report Template.docx” attached file is your template, with the data curves included. The “Notes Ball Toss Lab.pdf” file includes the notes I took as we went through the lab. The Lab 4-ball_toss.pdf” file is the description of the lab.

 
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Gravitation And Keplers Laws

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Lab 05 – Gravitation and Keplers Laws Name: _____________________

Why everyone in this class is attracted to everyone else.

https://phet.colorado.edu/en/simulation/gravity-force-lab

Adapted from Chris Bier’s Collisions PhET Lab Creative Commons LicenseOPTION A: CREATIVE COMMONS – ATTRIBUTION

 Introduction:

Every object around you is attracted to you. In fact, every object in the galaxy is attracted to every other object in the galaxy. Newton postulated and Cavendish confirmed that all objects with mass are attracted to all other objects with mass by a force that is proportional to their masses and inversely proportional to the square of the distance between the objects’ centers. This relationship became Newton’s Law of Universal Gravitation. In this simulation, you will look at two massive objects and their gravitational force between them to observe G, the constant of universal gravity that Cavendish investigated.

Important Formulas:Procedure: https://phet.colorado.edu/en/simulation/gravity-force-lab 

1. Take some time and familiarize yourself with the simulation. Notice how forces change as mass changes and as distance changes.

2. Fill out the chart below for the two objects at various distances.

3. Rearranging the equation for Force, you can CALCULATE the value of G using the values given below for m1, m2, and d, and the value for the Force that you obtain in the simulation. Record the force between the two object and then solve (calculate G) for the universal gravitation constant, G and compare it to values published in books, online, or your text book. The numbers you calculate for G will vary slightly from row to row. Remember significant digits! 15 pts

 

Mass Object 1 Mass Object 2 Distance Force Gravitation Constant,G

50.00 kg 25.00 kg 3.0m    
50.00 kg 25.00 kg 4.0m    
50.00 kg 25.00 kg 5.0m    
50.00 kg 25.00 kg 6.0m    
50.00 kg 25.00 kg 9.0m    

What do you notice about the force that acts on each object? 3 pts

[Answer Here]

Average value of G: _________________2 pts Units of G: _______________2 pts

Published value of G: ________________2 pts Source: _______________2 pts

How did your average value of G compare to the published value for G that you found? 3 pts

[Answer Here]

Conclusion Questions and Calculations: Bold and Underline the correct answer to each question.

1. Gravitational force is always attractive / repulsive. (circle) 2 pts

2. Newton’s 3rd Law tells us that if a gravitational force exists between two objects, one very massive and one less massive, then the force on the less massive object will be greater than / equal to / less than the force on the more massive object. 2 pts

3. The distance between masses is measured from their edges between them / from their centers / from the edge of one to the center of the other. 2 pts

4. As the distance between masses decreases, force increases / decreases. 2 pts

5. Doubling the mass of both masses would result in a change of force between the masses of 4x / 2x / no change / ½x / ¼x. 2 pts

6. Reducing the distance between two masses to half while doubling the mass of one of the masses would result in a change of force between the masses of 8x / 4x / no change / ½x / ¼x. 2 pts

7. What is the gravitational force between two students, Dylan and Sarah, if Dylan has a mass of 75 kg, Sarah has a mass of 54 kg, and their centers are separated by a distance of .45 m? 2 pts ________________ N

8. What is the gravitational force between two students, John and Mike, if John has a mass of 81 kg, Mike has a mass of 93 kg, and their centers are separated by a distance of .62 m? 2 pts ________________ N

9. Imagine a 4820 kg satellite in a geosynchronous orbit. If an 85 kg piece of space junk floats by at a distance of 3.5 m, what force will the space junk feel? 2 pts ________________ N

10. With what acceleration will the space junk move toward the satellite? 2 pts ______________ m/s2

11. With what acceleration will the satellite move (if any)? 2 pts ______________ m/s2

12. The gravitational force on the moon by the earth. 2 pts ________________ N

13. The gravitational force on the earth by the moon. 2 pts ________________ N

Show your calculation for 12 and 13 here.

The lab is continued on the next page.

Follow the directions carefully before answering the following questions.

Click http://phet.colorado.edu/en/simulation/gravity-and-orbits and Run Now

1) Run the Simulation, Keep all the default settings, but select the Earth and Satellite option. Turn on all of the options in the “Show” menu, then run and play with the simulation for a while. Which is experiencing a greater gravitational force: The satellite or the earth? 3 pts

[Answer Here]

2) Pause the Simulation. Hit “Reset”. (not “Reset All”). Alter the mass of the Satellite. Does the mass of the satellite have any impact on its Orbit? Explain. 3 pts

[Answer Here]

3) Pause the Simulation. Hit “Reset.” Click and drag the “v” at the end of the red velocity in order to decrease the satellite’s velocity.

a. What happens when you hit play? Why? 3 pts

[Answer Here]

b. Why doesn’t this happen to satellites normally? 3 pts

[Answer Here]

4) Pause the Simulation. Hit “Reset.” Click and drag to increase the satellite’s velocity. What happens when you hit play? Why? 3 pts

[Answer Here]

5) Pause the Simulation. Hit “Reset.” Click and drag the satellite itself to move it further away from earth. What happens when you hit play? Why? 3 pts

[Answer Here]

6) Try to create another stable orbit that is further or closer to earth. What other very important variable would you need to alter with this new orbit? 3 pts

[Answer Here]

7) Just for fun. Click and drag earth to create a very small velocity for earth. Can the satellite still orbit a moving planet? 3 pts

[Answer Here]

8) Pause the Simulation. Hit “Reset.” On the top left tabs, change your view so that you are to scale. In the Show menu, you can now also turn on the “Tape Measure”. Run the simulation, with the path shown.

How far out is the satellite? 3 pts

[Answer Here]

How long does it take for the satellite to orbit earth? 3 pts

[Answer Here]

9) Switch modes, so that you are now looking at just the earth and the moon.

How far is the moon? 3 pts

[Answer Here]

How long does it take for the moon to orbit the earth? 3 pts

[Answer Here]

10) Again Switch modes, so that you are now looking at just the earth and the sun.

How far is the earth from the sun? 3 pts

[Answer Here]

How long does it take for the earth to orbit the sun? 3 pts

[Answer Here]

11)

According to Kepler’s third law, the time it takes for one complete orbit is proportional to the mean distance between the centers of two bodies. T2 ≈ r3. When a constant is included, the equation is . Use the adjustable mass controls on the simulation of just the earth and sun to determine what mass the “m” in Kepler’s equation must refer to. Is it the mass of the orbiting object or the mass of the central object?12) Kepler actually proposed three laws.

Kepler’s Laws of Planetary Motion

First Law: Each planet travels in an elliptical orbit around the sun, and the sun is at one of the focal points.

Second Law: An imaginary line drawn from the sun to any planet sweeps out equal areas in equal time intervals.

Third Law: The square of a planet’s orbital period ( T2 ) is proportional to the cube of the average distance ( r3 ) between the planet and the sun, or T2 r3 .

An Illustration of Keplers 1st and 2nd Laws is Shown here: A1=A2. In this case you can see that when a planet is closer to the sun then it must cover more distance in the same time. It must move faster.

Reset all. Select the Earth and Sun. Choose to show only the path and velocities. Manipulate the Simulation until you achieve an elliptical orbit. The speed of the earth increases slightly as it orbits closer to the sun but decreases slightly when it is further from the sun. (hint: move the sun itself.) Do a print screen. Then paste it below into this document. 8 pts

Page 1 of 5

 

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Resistivity Experiment .. Introduction And Conclusion

/in /by

1

Resistivity Equipment

Qty Item Parts Number

1 Voltage Source

1 Resistance Apparatus EM-8812

1 Sample Wire Set EM-8813

1 Voltage Sensor UI-5100

2 Patch Cords

Purpose The purpose of this activity is to examine how the resistance of a resistor is determined via geometry of

the resistor, and the material which it is made of. Also, to further the student’s understanding of the

difference between resistance, and resistivity.

Theory Ohm’s Law describes the relationship between the resistance R of a wire, the voltage drop across it V,

and the current through the wire I. This is formally given by the equation;

𝐼 = 𝑉

𝑅

The resistance of the wire is a function of both the geometry of the wire, and the material that the wire

is composed of. This is formally given by the equation;

𝑅 = 𝜌 𝐿

𝐴

Where here L is the length of the wire, A is the cross-section area of the wire (in this simple equation we

are assuming the cross-section area is constant along the entire length of the wire), and 𝜌 is the

resistivity of the material the wire is composed of. The SI units of resistivity are Ohms·meters, Ω·m, and

it is a quantification of how difficult it is to move a current through a length of the material. This

equation shows us that resistance is a property of the object, while resistivity is a property of the

material the object is made of. Due to this distinction it is really incorrect to say things like, “Copper has

a low resistance.” Because Copper has a ‘low’ resistivity. If you take a Copper wire and double its length

you double the

resistance of that

wire, but the value

of the resistivity of

the copper in that

wire doesn’t

change.

2

Setup

1. Open the Capstone software. On the left side of the main screen is the Tool Bar. Click on the

Hardware Setup icon. This will open the Setup window.

 Click on Analog Channel A of the picture of the 850 Universal Interface in the Setup

window, and then scroll down, and add the ‘Voltage Sensor’.

 Click on Output Channel 1 of the picture of the 850 Universal Interface in the Setup

window, and then scroll down, and add the ‘Output Voltage-Current Sensor’.

2. On the bottom center left of the main screen the Sample Rate Tab should now say ‘

Common Rate’.

 Set the Sample Rate to 1 Hz.

3. In the Tool Bar, now click on the Signal Generator Icon. This will open the Signal Generator

window.

 In the Signal Generator window click on the tab “850 output 1” tab. This will open up

the options window for the output generator 1.

 Set the Waveform to a “DC”.

 Set the DC Voltage to 2 volts.

 Set the Voltage Limit to 2 volts.

 Set the Current Limit to 1.1 A.

 Set the Generator to “Auto”, so that it will start and stop automatically when you start

and stop collecting data.

4. Close the Tool Bar.

5. In the main window click on the ‘Two Displays” option. (Bottom left option). A two display

window should appear.

6. In the Display Bar, on the right side of the main screen, click and hold down the ‘digits’ icon,

then drag it out to the top display, and then release. Repeat for the bottom display as well.

7. For the top digits display click on ‘select measurement’ and select ‘Voltage Ch A (V)’

8. For the bottom digits display click on ‘select measurement’ and select ‘Output Voltage, Ch 1 (V)’.

9. Putting a wire in the Resistance Apparatus.

 Move the Reference Probe, and the Slider Probe to their “parked” positions.

 Twist the two black handles counterclockwise to open the clamps to allow the wire to

slide into position.

 Slide the 0.050 inch diameter Brass wire into position such that each end passes

underneath both a probe, and one of the clamps.

3

 Tighten the clamps to hold the wire in place, but don’t tighten too much. As soon as you

get a little resistance stop tightening.

10. Plug in the Voltage sensor to Analog Ch A, then plug the two ends of the voltage sensor into the

two slots on the probes of the apparatus. Black into black, and red into red.

11. Plug to patch cords into Output Ch 1, (top right of the 850 Universal Interface). Then plug one

patch cord into each of the power slots on the apparatus. Again, black into black, and red into

red.

12. On the main widow select the ‘Two Large Digits’ template.

 Click on the top ‘Select Measurement’ tab, and select Voltage, Ch A(V).

 Click on the bottom ‘Select Measurement’ tab, and select Output Current, Ch 01(A).

4

Procedure

1. Move the Reference Probe to the 0.0 cm position, and move the Slider Probe to the 5.0 cm

Position.

2. Click on Record, at the bottom left of the main screen.

 The Record tab should now be a Stop tab. Immediately click stop.

 Record the values for Voltage, and current in Table “Copper, 0.127cm”

3. Then repeat step two for the Slider Probe in positions 10.0 cm, 15,0 cm, and 20.0 cm.

4. Return both the Reference Probe, and the Slider Probe to their parked positions.

5. Then untighten the two black handles, and remove the brass wire.

6. Now repeat for the following wires: Brass 0.040 in, 0.032 in, 0.020 in.

5

6

Analysis Brass 0.050 inch Diameter Cross-Section Area__________________

L(cm) L/A(cm-1) V(V) i(A) V/i=R(Ω) R(µΩ)

1. Complete the chart. Show work. (10 points)

2. In Excel plot Resistance (µΩ) vs Length/Area, and show the treadline on the graph. What are the

units of the slope of this graph, and what physical quantity does it represent? (8 points)

7

Brass 0.040 inch Diameter Cross-Section Area__________________

L(cm) L/A(cm-1) V(V) i(A) V/i=R(Ω) R(µΩ)

3. Complete the chart. Show work.(10 points)

4. In Excel plot Resistance (µΩ) vs Length/Area, and show the treadline on the graph. What are the

units of the slope of this graph, and what physical quantity does it represent? (8 points)

8

Brass 0.032 inch Diameter Cross-Section Area__________________

L(cm) L/A(cm-1) V(V) i(A) V/i=R(Ω) R(µΩ)

5. Complete the chart. Show work. (10 points)

6. In Excel plot Resistance (µΩ) vs Length/Area, and show the treadline on the graph. What are the

units of the slope of this graph, and what physical quantity does it represent? (8 points)

9

Brass 0.020 inch Diameter Cross-Section Area__________________

L(cm) L/A(cm-1) V(V) i(A) V/i=R(Ω) R(µΩ)

7. Complete the chart. Show work. (10 points)

8. In Excel plot Resistance (µΩ) vs Length/Area, and show the treadline on the graph. What are the

units of the slope of this graph, and what physical quantity does it represent? (8 points)

9. Calculate the average value of your slopes, then calculate the % error between it, and the

accepted value. (8 points)

 
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