Work, Power, and Conservation of Energy Review Questions

1)At point C, the bob in the pendulum has ___ Ug and ___ K A)maximum, maximum B)maximum, minimum C)minimum, minimum D)minimum, maximum E)Ug is equal to K at point C

2)A ball with a mass m, moves down the slide 2)A ball with a mass m, moves down the slide. As it descends, its gravitational potential energy A)increases because kinetic energy increases B)decreases as it transforms into kinetic energy C)remains the same as potential energy is always conserved

3) A boy on a roller coaster cart is released from rest from the point shown on the diagram below, will the boy in the cart be able to complete the loop and exit successfully? Neglect friction A)yes B)No

4)At points A and E, the bob in the pendulum has ___ Ug and ___ K A)maximum, maximum B)maximum, minimum C)minimum, minimum D)minimum, maximum E)Ug is equal to K at points A and E

5) A 2-kg ball rests on top of a track, point A, before release 5) A 2-kg ball rests on top of a track, point A, before release. Once the ball is released, the ball slides down the track. Calculate the total mechanical energy in the system.

6) A 2-kg ball rests on top of a track, point A, before release 6) A 2-kg ball rests on top of a track, point A, before release. Once the ball is released, the ball slides down the track. Find its kinetic energy when it’s passing through point C.

7) A ball is dropped from rest from Position 1 7) A ball is dropped from rest from Position 1. How much potential energy has been used by the time the ball reaches Position 2? Neglect air resistance. A)1000 J B)540 J C)460 J D)none of the answers

8)A 1-kg ball rests on top of a track, point A, before release 8)A 1-kg ball rests on top of a track, point A, before release. Once the ball is released, the ball slides down the track. At which point will the sum of the potential and the kinetic energies be at its maximum? A)A B)B C)C D)D E)E F)F G)it will be the same throughout

9) A ball is dropped from rest from Position 1 9) A ball is dropped from rest from Position 1. With how much kinetic energy does the ball strike the floor? Neglect air resistance. A)1000 J B)540 J C)460 J D)none of the answers

10)Find the minimum kinetic energy the cart must have to be able to make it to the top of the ramp 10 meters above the ground.

11)If the 1-kg ball is released from rest at point B, how high will it go? Neglect friction and air resistance A)0 m B)10 m C)20 m D)30 m E)40 m F)impossible to know

12) A roller coaster cart is released from rest from the point shown on the diagram below. Will the cart be able to reach point B? Neglect friction and air resistance A)Yes B)No

13) A 2-kg ball rests on top of the track 5 m above the ground 13) A 2-kg ball rests on top of the track 5 m above the ground. If the ball rolls down the track from point A and its speed at point B is 9 m/s, how much energy was “lost” to friction and air resistance?

14) A ball is dropped from rest from Position 1 14) A ball is dropped from rest from Position 1. How much potential energy is left by the time the ball reaches Position 2? Neglect air resistance. A)1000 J B)540 J C)460 J D)none of the answers

15) The information on the roller coaster cart is as following: height at current position = 10 m, mass with people on it = 100 kg, speed at the instant shown = 10 m/s. Find the total energy in the system.

16)If the total energy in the system is 20,000 J, will the 100-kg cart be able to reach point B located 15 meters above the ground? A)Yes B)No

17)If the 1-kg ball is released from rest at point A, what will its speed be at point C?

18)If the 1-kg ball is released from rest at point A, what will its speed be at point E?

19) A 1-kg ball is dropped from a height of 2 meters (I) 19) A 1-kg ball is dropped from a height of 2 meters (I). When the ball hits the floor, it bounces up to a height of 1.6 meters (II). How much energy was lost to the environment?

20)If the 1-kg ball is released from rest at point A, how high on the rollercoaster will it be when it is moving at 10 m/s?

21) Find the work done by the force.

22) Three balls with identical masses follow the trajectories shown 22) Three balls with identical masses follow the trajectories shown. Which ball strikes the ground with the most energy? A) 1 B) 2 C) 3 D) all the same

23) As the purple box moves to the right, the frictional force is responsible for doing A) positive work on the box. B) negative work on the box. C) zero work on the box.

24) A 75-kg rock was lifted and placed on top of a column 4 meters from the ground. How much work was done on the rock?

25) Let’s say you need to carry a package from Start to Finish 25) Let’s say you need to carry a package from Start to Finish. Through which path would the package acquire the most gravitational potential energy? A B C All the same

26)A 2-kg object is moved 5 m by a 100 N force at an angle of 30o 26)A 2-kg object is moved 5 m by a 100 N force at an angle of 30o. If the force of friction is 20 N, how much work is the 100 N force doing on the object?

27)A 2-kg object is moved 5 m by a 100 N force at an angle of 30o 27)A 2-kg object is moved 5 m by a 100 N force at an angle of 30o. If the force of friction is 20 N, how much work is friction doing on the object?

28)Find the minimum speed the cart must have to be able to make it to the top of the ramp 10 meters above the ground.

29)The kid pulls the crate that has a weight of 200 N, a distance of 2 meters. How much work did the kid do on the crate? do on the crate? A)0 J B)100 J C)400 J D)more information is needed

30) It takes the weightlifter 2 seconds to lift the weights 2 m 30) It takes the weightlifter 2 seconds to lift the weights 2 m. How much power does he use every time he lifts the weights?

31) A force caused the following cart to go from rest to 4 m/s 31) A force caused the following cart to go from rest to 4 m/s. How much work was done on the cart?

32) A force caused the following cart to go from 2 m/s to 4 m/s 32) A force caused the following cart to go from 2 m/s to 4 m/s. How much work was done on the cart?

33)The work done by the 20 N force on the 5-kg box from A to B is 600 J. The calculated gravitational potential energy of the box at point B is only 500 J. Explain what might have happened to the missing 100 J of energy.