Problem Solving

Unit II Problem Solving Worksheet

This assignment will allow you to demonstrate the following objectives:

• Illustrate the scientific method within everyday situations. o Identify the appropriate formulas necessary to solve specific scenario questions. o Calculate and analyze the acceleration and the force in various situations.

• Explain Newton’s laws of motion at work in common phenomena. o Solve problems using mass and weight. o Explore the relationship between the first and second laws. o Identify action-reaction pairs in the third law.

Instructions: Choose 8 of the 10 problems below. Show your work in detail. Answer the questions directly in this tem- plate. Before doing this, it is highly recommending that you thoroughly review the three examples in the Unit Lesson.

1. Susan pushes her dad, David, on an ice rink with a force of 30 N. She weighs 45 kg and her dad weighs 100 kg. What are the accelerations of Susan and David?

Hint: For an example of this problem being worked out click here. To view a transcript of this video, click here.

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2. Alice holds a black belt in Taekwondo and her fist has a mass of 0.5 kg. Her fist obtains a velocity of 5 m/s in 0.1 seconds from rest. Evaluate the average net force applied to the fist.

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3. A lunar exploration vehicle was created by a research team. It weighs 3,000 kg on the earth. It needs an accelera- tion of 10 m/s2 on the moon. In order to have the same acceleration, what will be the net force acting on the vehi- cle on the earth? To view a transcript of this video, click here (Unit II PS_3.docx). Also, click here(Unit II PS_3.pptx) to review the power point presentation.

Hint: For an example of this problem being worked out click here. To view a transcript of this video, click here.

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Unit II Problem Solving Worksheet 4. Three people are pushing a 500 kg of box in the same direction. Applied forces are 30 N, 20 N,

and 10 N respectively. If the acceleration of the box is 0.02 m/s2, what is the magnitude of a force created by fric- tion?

 

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5. You drive a 6,000 kg boat due north, while the wind exerts a force of 600 N due south and the water exerts a re- sistive force of 1,200 N due south. The generated force by the boat’s engines is 4,200 N. Find the magnitude and direction of the boat’s acceleration.

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6. A machine accelerates a 5 kg missile from rest to a speed of 5 km/s. The net force accelerating the missile 500,000 N. How long does it take to arrive at the speed of 5 km/s?

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7. Peter found an amazing fact in an amusement park when he tried to ride the Magic Mountain Superman. Powerful magnets accelerate a car and its riders from zero to 45 m/s in 7 seconds. Suppose the mass of the car and riders is 5,600 kg. What is the average net force exerted on the car and riders by the magnets?

Hint: For an example of this problem being worked out click here. To view a transcript of this video, click here.

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8. Two forces of 10 N and 30 N are applied to a 10 kg box. Find (1) the box’s acceleration when both forces point due east and (2) the box’s acceleration when 10 N force points due east and 30 N force points due west.

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9. When a 60 g (=0.06 kg) tennis ball is served by a newly invented machine, it accelerates from zero to 50 m/s. The ball experiences a constant acceleration due to the impact with the racket over a distance of 0.5 m. What is the net force acting on the ball? Use the formula: a= (vf2-vi2)/2d regarding the relation among acceleration a, final ve- locity vf, initial velocity vi and the traveled distance of an object d.

Hint: For an example of this problem being worked out click here. To view a transcript of this video, click here.

?

20 N

30 N

8810 N

 

 

Unit II Problem Solving Worksheet

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10. Cole is riding a sled with initial speed of 5 m/s from west to east. The frictional force of 50 N exists due west. The mass of the sled and Cole together is 100 kg. How far does the sled go before stopping? Use the formula: a= (vf2- vi2)/2d regarding the relation among acceleration a, final velocity vf, initial velocity vi and the traveled distance of an object d.

Hint: For an example of this problem being worked out click here. To view a transcript of this video, click here.

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