Energy Freedman - Wappingers Central School District

Energy

Freedman

1. The diagram below shows block A, having mass 2m and speed v, and block B having mass m and speed 2v.

6. Which graph best represents the relationship between the kinetic energy, KE, and the velocity of an object accelerating in a straight line?

A)

Compared to the kinetic energy of block A, the kinetic energy of block B is

A) the same

B) twice as great

C) one-half as great

D) four times as great

B)

2. If the direction of a moving car changes and its speed remains constant, which quantity must remain the same?

A) velocity

B) momentum

C) displacement

D) kinetic energy

C)

3. A 60.0-kilogram runner has 1920 joules of kinetic energy. At what speed is she running?

A) 5.66 m/s C) 32.0 m/s

B) 8.00 m/s D) 64.0 m/s

D)

4. A 45.0-kilogram boy is riding a 15.0-kilogram bicycle with a speed of 8.00 meters per second. What is the combined kinetic energy of the boy and the bicycle?

A) 240. J C) 1440 J

B) 480. J D) 1920 J

5. If the speed of a car is doubled, the kinetic energy of the car is

A) quadrupled C) doubled

B) quartered D) halved

7. A 1.0-kilogram rubber ball traveling east at 4.0 meters per second hits a wall and bounces back toward the west at 2.0 meters per second. Compared to the kinetic energy of the ball before it hits the wall, the kinetic energy of the ball after it bounces off the wall is

A) one-fourth as great B) one-half as great

C) the same

D) four times as great

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8. A 1.0-kilogram book resting on the ground is moved 1.0 meter at various angles relative to the horizontal. In which direction does the 1.0-meter displacement produce the greatest increase in the book's gravitational potential energy? A)

B)

C)

D)

9. What is the gravitational potential energy with respect to the surface of the water of a 75.0 kilogram diver located 3.00 meters above the water?

A) 2.17 104 J C) 2.25 102 J

B) 2.21 103 J D) 2.29 101 J

10. An object weighing 15 Newtons is lifted from the ground to a height of 0.22 meter. The increase in the object's gravitational potential energy is approximately

A) 310 J B) 32 J C) 3.3 J D) 0.34 J

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11. Which graph best represents the relationship between the gravitational potential energy of a freely falling object and the object's height above the ground near the surface of Earth?

A)

B)

C)

D)

12. Two weightlifters, one 1.5 meters tall and one 2.0 meters tall, raise identical 50.-kilogram masses above their heads. Compared to the work done by the weightlifter who is 1.5 meters tall, the work done by the weightlifter who is 2.0 meters tall is

A) less C) the same

B) greater

14. The diagram below shows a 50.-kilogram crate on a frictionless plane at angle to the horizontal. The crate is pushed at constant speed up the incline from point A to point B by force F.

13. A student does 60. joules of work pushing a 3.0-kilogram box up the full length of a ramp that is 5.0 meters long. What is the magnitude of the force applied to the box to do this work?

A) 20. N B) 15 N C) 12 N D) 4.0 N

If angle were increased, what would be the effect on the magnitude of force F and the total work W done on the crate as it is moved from A to B?

A) W would remain the same and the magnitude of F would decrease.

B) W would remain the same and the magnitude of F would increase.

C) W would increase and the magnitude of F would decrease.

D) W would increase and the magnitude of F would increase.

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15. The diagram below shows points A, B, and C at or near Earth's surface. As a mass is moved from A to B, 100. joules of work are done against gravity.

20. A 40.-kilogram student runs up a staircase to a floor that is 5.0 meters higher than her starting point in 7.0 seconds. The student's power output is

A) 29 W C) 1.4 ? 103 W

B) 280 W D) 1.4 ? 104 W

21. The graph below represents the relationship between the work done by a student running up a flight of stairs and the time of ascent.

What is the amount of work done against gravity as an identical mass is moved from A to C?

A) 100. J B) 200. J C) 173 J D) 273 J

16. A constant force of 1900 Newtons is required to keep an automobile having a mass of 1.0 ? 103 kilograms moving at a constant speed of 20. meters per second. The work done in moving the automobile a distance of 2.0 ? 103 meters is

A) 2.0 ? 104J C) 2.0 ? 106 J

B) 3.8 ? 104J D) 3.8 ? 106 J

17. Which combination of units can be used to express work? A) newton ? second meter B) newton ? meter second C) newton/meter D) newton ? meter

18. In the diagram below, a 20.0-newton force is used to push a 2.00-kilogram cart a distance of 5.00 meters.

The work done on the cart is A) 100. J B) 200. J C) 150. J D) 40.0 J

19. A student applies a 20.-newton force to move a crate at a constant speed of 4.0 meters per second across a rough floor. How much work is done by the student on the crate in 6.0 seconds? A) 80. J B) 120 J C) 240 J D) 480 J

What does the slope of this graph represent?

A) impulse C) speed

B) momentum D) power

22. In raising an object vertically at a constant speed of 2.0 meters per second, 10. watts of power is developed. The weight of the object is

A) 5.0 N B) 20. N C) 40. N D) 50. N

23. A 2000-watt motor working at full capacity can vertically lift a 400-newton weight at a constant speed of

A) 2 ? 103 m/s C) 5 m/s

B) 50 m/s D) 0.2 m/s

24. A boat weighing 9.0 ? 102 Newtons requires a horizontal force of 6.0 ? 102 Newtons to move it across the water at 1.5 ? 101 meters per second. The boat's engine must provide energy at the rate of

A) 2.5 ? 10?2 J C) 7.5 ? 103 J

B) 4.0 ? 101 W D) 9.0 ? 103 W

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25. A 95-kilogram student climbs 4.0 meters up a rope in 3.0 seconds. What is the power output of the student?

A) 1.3 ? 102 W C) 1.2 ? 103 W

B) 3.8 ? 102 W D) 3.7 ? 103 W

31. The diagram below shows a moving, 5.00-kilogram cart at the foot of a hill 10.0 meters high. For the cart to reach the top of the hill, what is the minimum kinetic energy of the cart in the position shown? [Neglect energy loss due to friction.]

26. A motor used 120. watts of power to raise a 15-newton object in 5.0 seconds. Through what vertical distance was the object raised?

A) 1.6 m B) 8.0 m C) 40. m D) 360 m

A) 4.91 J B) 50.0 J C) 250. J D) 491 J

27. A 3.0-kilogram block is initially at rest on a frictionless, horizontal surface. The block is moved 8.0 meters in 2.0 seconds by the application of a 12-newton horizontal force, as shown in the diagram below.

32. A 1-kilogram rock is dropped from a cliff 90 meters high. After falling 20 meters, the kinetic energy of the rock is approximately

A) 20 J B) 200 J C) 700 J D) 900 J

33. As a ball falls freely (without friction) toward the ground, its total mechanical energy

What is the average power developed while moving the block?

A) decreases

B) increases

C) remains the same

A) 24 W B) 32 W C) 48 W D) 96 W

34. As an object falls freely, the kinetic energy of the object

28. A motor having a power rating of 500. watts is used to lift an object weighing 100. Newtons. How much time does the motor take to lift the object a vertical distance of 10.0 meters?

A) 0.500 s C) 5.00 s

B) 2.00 s D) 50.0 s

29. What is the maximum height to which a 1200-watt motor could lift an object weighing 200. Newtons in 4.0 seconds?

A) 0.67 m C) 6.0 m

B) 1.5 m D) 24 m

A) decreases C) remains the same

B) increases

35. Which device transforms mechanical energy into electrical energy?

A) generator C) transformer

B) motor D) mass spectrometer

36. As shown in the diagram below, a student exerts an average force of 600. newtons on a rope to lift a 50.0-kilogram crate a vertical distance of 3.00 meters.

30. A 0.50-kilogram ball is thrown vertically upward with an initial kinetic energy of 25 joules. Approximately how high will the ball rise? [Neglect air resistance.]

A) 2.6 m B) 5.1 m C) 13 m D) 25 m

Compared to the work done by the student, the gravitational potential energy gained by the crate is

A) exactly the same C) 330 J more

B) 330 J less D) 150 J more

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