Name: Class: Date: S15--AP Q1 Work and Energy PRACTICE Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Rupel pushes a box 5.00 m by applying a 25.0-N horizontal force. What work does she do? a. 10.0 J b. 25.0 J c. 125 J d. 550 J e. 750 J 2. A worker pushes a wheelbarrow with a force of 40 N over a level distance of 6.0 m. If a frictional force of 24 N acts on the wheelbarrow in a direction opposite to that of the worker, what net work is done on the wheelbarrow? a. 240 J b. 216 J c. 144 J d. 96 J e. 75 J 3. The work done by static friction can be: a. positive. b. negative. c. zero. d. nonnegative. e. Any of the above. 4. A satellite is held in orbit by a 2 000-N gravitational force. Each time the satellite completes an orbit of circumference 80 000 km, the work done on it by gravity is: a. 1.6 10 8 J. b. 1.6 10 11 J. c. 6.4 10 11 J. d. 0. e. None of the above. 5. Which of the following is that form of energy associated with an object's location in a conservative force field? a. potential b. thermal c. bio-chemical d. kinetic e. nuclear 6. A golf ball hits a wall and bounces back at 3/4 the original speed. What part of the original kinetic energy of the ball did it lose in the collision? a. 1/4 b. 3/8 c. 7/16 d. 9/16 e. 11/16 7. A 1 200-kg automobile moving at 25 m/s has the brakes applied with a deceleration of 8.0 m/s 2. How far does the car travel before it stops? a. 39 m b. 47 m c. 55 m d. 63 m e. 72 m 8. A professional skier reaches a speed of 56 m/s on a 30 ski slope. Ignoring friction, what was the minimum distance along the slope the skier would have had to travel, starting from rest? a. 110 m b. 160 m c. 320 m d. 640 m e. 720 m 9. Samantha pushes a 50-N crate up a ramp 25.0 m in length and inclined at 10 with the horizontal. What potential energy change does the crate experience? a. 13 J b. 55 J c. 120 J d. 220 J e. 280 J 10. A 15.0-kg crate, initially at rest, slides down a ramp 2.0 m long and inclined at an angle of 20 with the horizontal. If there is no friction between ramp surface and crate, what is the kinetic energy of the crate at the bottom of the ramp? (g = 9.8 m/s 2 ) a. 220 J b. 690 J c. 10 J d. 100 J e. 140 J 11. A 10.0-kg box starts at rest and slides 3.5 m down a ramp inclined at an angle of 10 with the horizontal. If there is no friction between the ramp surface and crate, what is the velocity of the crate at the bottom of the ramp? (g = 9.8 m/s 2 ) a. 6.1 m/s b. 3.5 m/s c. 10.7 m/s d. 8.3 m/s e. 4.8 m/s 12. A baseball catcher puts on an exhibition by catching a 0.15-kg ball dropped from a helicopter at a height of 101 m. What is the speed of the ball just before it hits the catcher's glove 1.0 m above the ground? (g = 9.8 m/s 2 and ignore air resistance) a. 44 m/s b. 38 m/s c. 31 m/s d. 22 m/s e. 15 m/s 1
Name: 13. A simple pendulum, 2.0 m in length, is released by a push when the support string is at an angle of 25 from the vertical. If the initial speed of the suspended mass is 1.2 m/s when at the release point, to what maximum angle will it move in the second half of its swing? a. 37 b. 30 c. 27 d. 21 e. 17 14. Old Faithful geyser in Yellowstone Park shoots water hourly to a height of 40 m. With what velocity does the water leave the ground? a. 7.0 m/s b. 14 m/s c. 20 m/s d. 28 m/s e. 34 m/s 15. A pole vaulter clears 6.00 m. With what speed does he strike the mat in the landing area? a. 2.70 m/s b. 5.40 m/s c. 10.8 m/s d. 21.6 m/s e. 26.7 m/s 16. A 2 000-kg ore car rolls 50.0 m down a frictionless 10.0 incline. If there is a horizontal spring at the end of the incline, what spring constant is required to stop the ore car in a distance of 1.00 m? a. 340 kn/m b. 681 kn/m c. 980 kn/m d. 1 960 kn/m e. 2 100 kn/m 17. The SI units for k, the spring constant, are equivalent to: a. J. b. J / N. c. kg / s 2. d. kg / s. e. None of the above. 18. By how much is the energy stored in a Hooke's law spring increased when its stretch is increased from 8.00 cm to 16.0 cm? a. 100% b. 200% c. 300 % d. 400 % e. The correct answer is not given. 19. A Hooke's law spring is compressed 12.0 cm from equilibrium, and the potential energy stored is 72.0 J. What compression (as measured from equilibrium) would result in 100 J being stored in this case? a. 16.7 cm b. 14.1 cm c. 13.6 cm d. 12.8 cm e. No answer is correct. 20. A Hooke's law spring is mounted horizontally over a frictionless surface. The spring is then compressed a distance d and is used to launch a mass m along the frictionless surface. What compression of the spring would result in the mass attaining double the kinetic energy received in the above situation? a. 1.41 d b. 1.73 d c. 2.00 d d. 4.00 d e. 5.35 d 21. A Hooke's law spring is mounted horizontally over a frictionless surface. The spring is then compressed a distance d and is used to launch a mass m along the frictionless surface. What compression of the spring would result in the mass attaining double the speed received in the above situation? a. 1.41 d b. 1.73 d c. 2.00 d d. 4.00 d e. 5.35 d 22. A 50-N crate is pulled up a 5-m inclined plane by a worker at constant velocity. If the plane is inclined at an angle of 37 to the horizontal and there exists a constant frictional force of 10 N between the crate and the surface, what is the force applied by the worker? a. zero b. 20 N c. 30 N d. 40 N e. 50 N 23. Adisa pulls a 40-N crate up a 5.0-m long inclined plane at a constant velocity. If the plane is inclined at an angle of 37 to the horizontal and there is a constant force of friction of 10 N between the crate and the surface, what is the net change in potential energy of the crate? a. 120 J b. 120 J c. 200 J d. 200 J e. 140 J 24. A baseball catcher puts on an exhibition by catching a 0.150-kg ball dropped from a helicopter at a height of 100 m above the catcher. If the catcher "gives" with the ball for a distance of 0.750 m while catching it, what average force is exerted on the mitt by the ball? (g = 9.80 m/s 2 ) a. 78 N b. 119 N c. 197 N d. 392 N e. 435 N 2
Name: 25. A Hooke's law spring is compressed a distance d and is used to launch a mass m vertically to a height h above its starting position. Under the same compression d, the spring is now used to launch a mass of 2m. How high does this second mass rise? a. h b. h/2 c. h/1.41 d. h/4 e. h/8 26. A Hooke's law spring is compressed a distance d and is used to launch a particle of mass m vertically to a height h above its starting position. Under double the compression, the spring is now used to launch a particle of mass 2 m. How high does the second mass rise above its starting position? a. h b. 2 h c. 3 h d. 4 h e. 5 h 27. The quantity of work equal to one joule is also equivalent to which of the following? a. watt b. watt /s c. watt s d. watt /s 2 e. watt s 2 28. The unit of power, watt, is dimensionally the same as: a. joule-second. b. joule/second. c. joule-meter. d. joule/meter. e. joule-kilogram. 29. A 60-kg woman runs up a flight of stairs having a rise of 4.0 m in a time of 4.2 s. What average power did she supply? a. 380 W b. 560 W c. 620 W d. 670 W e. 730 W 30. An automobile delivers 30.0 hp to its wheels when moving at a constant speed of 22.0 m/s. What is the resistance force on the automobile at this speed? (1 hp = 746 watts) a. 18 600 N b. 410 000 N c. 1 020 N d. 848 N e. 763 N 31. A jet engine develops 1.0 10 5 N of thrust in moving an airplane forward at a speed of 900 km/h. What is the power developed by the engine? a. 500 kw b. 10 MW c. 25 MW d. 50 MW e. 65 MW 32. Water flows over a section of Niagara Falls at a rate of 1.20 10 6 kg/s and falls 50.0 m. What is the power dissipated by the waterfall? a. 588 MW b. 294 MW c. 147 MW d. 60.0 MW e. 25.0 MW 33. A 1 000-kg sports car accelerates from zero to 25 m/s in 7.5 s. What is the average power delivered by the automobile engine? a. 20.8 kw b. 30.3 kw c. 41.7 kw d. 52.4 kw e. 67.8 kw 34. A 100-W light bulb is left on for 10.0 hours. Over this period of time, how much energy was used by the bulb? a. 1 000 J b. 3 600 J c. 3 600 000 J d. 1.34 hp e. 1 000 000 J 35. The area under the force vs. displacement curve represents: a. area. b. force. c. work. d. coefficient of static friction. e. power. 36. A force of 100 N is applied to a 50-kg mass in the direction of motion for a distance of 6.0 m and then the force is increased to 150 N for the next 4.0 m. For the 10 m of travel, how much work is done by the varying force? a. 1 200 J b. 1 500 J c. 2 400 J d. -1 500 J e. -2 400 J 37. The net force acting on a 6.0-kg object is given by F x = (10 - x) N, where F x is in newtons and x is in meters. How much work is done on the object as it moves from x = 0 to x = 10 m? a. 100 J b. 75 J c. 50 J d. 25 J e. 20 J 38. The net force acting on a 12.6-kg object is given by F x = (20 - x) N, where F x is in newtons and x is in meters. How much work is done on the object as it moves from x = 0 to x = 10 m? a. 300 J b. 200 J c. 150 J d. 100 J e. 50 J 3
Name: 39. The unit of work, joule, is dimensionally the same as: a. newton/second. b. newton/kilogram. c. newton-second. d. newton-meter. e. newton/meter. 40. Which of the following is an example of a nonconservative force? a. gravity b. magnetism c. friction d. Both choices A and B are valid. e. Both choices A and C are valid. 4
S15--AP Q1 Work and Energy PRACTICE Answer Section MULTIPLE CHOICE 1. ANS: C PTS: 1 DIF: 1 TOP: 5.1 Work 2. ANS: D PTS: 1 DIF: 2 TOP: 5.1 Work 3. ANS: E PTS: 1 DIF: 2 TOP: 5.1 Work 4. ANS: D PTS: 1 DIF: 2 TOP: 5.1 Work 5. ANS: A PTS: 1 DIF: 1 6. ANS: C PTS: 1 DIF: 2 7. ANS: A PTS: 1 DIF: 2 8. ANS: C PTS: 1 DIF: 2 TOP: 5.3 Gravitational Potential Energy 9. ANS: D PTS: 1 DIF: 1 TOP: 5.3 Gravitational Potential Energy 10. ANS: D PTS: 1 DIF: 2 TOP: 5.3 Gravitational Potential Energy 11. ANS: B PTS: 1 DIF: 2 TOP: 5.3 Gravitational Potential Energy 12. ANS: A PTS: 1 DIF: 2 TOP: 5.3 Gravitational Potential Energy 13. ANS: B PTS: 1 DIF: 3 TOP: 5.3 Gravitational Potential Energy 14. ANS: D PTS: 1 DIF: 2 TOP: 5.3 Gravitational Potential Energy 15. ANS: C PTS: 1 DIF: 2 TOP: 5.3 Gravitational Potential Energy 16. ANS: A PTS: 1 DIF: 2 TOP: 5.4 Spring Potential Energy 17. ANS: C PTS: 1 DIF: 2 TOP: 5.4 Spring Potential Energy 18. ANS: C PTS: 1 DIF: 2 TOP: 5.4 Spring Potential Energy 19. ANS: B PTS: 1 DIF: 3 TOP: 5.4 Spring Potential Energy 20. ANS: A PTS: 1 DIF: 2 TOP: 5.4 Spring Potential Energy 21. ANS: C PTS: 1 DIF: 3 TOP: 5.4 Spring Potential Energy 22. ANS: D PTS: 1 DIF: 2 TOP: 5.5 Systems and Energy Conservation 23. ANS: A PTS: 1 DIF: 2 TOP: 5.5 Systems and Energy Conservation 24. ANS: C PTS: 1 DIF: 2 TOP: 5.5 Systems and Energy Conservation 25. ANS: B PTS: 1 DIF: 2 TOP: 5.5 Systems and Energy Conservation 26. ANS: B PTS: 1 DIF: 2 TOP: 5.5 Systems and Energy Conservation 27. ANS: C PTS: 1 DIF: 1 TOP: 5.6 Power 28. ANS: B PTS: 1 DIF: 1 TOP: 5.6 Power 29. ANS: B PTS: 1 DIF: 2 TOP: 5.6 Power 30. ANS: C PTS: 1 DIF: 2 TOP: 5.6 Power 31. ANS: C PTS: 1 DIF: 2 TOP: 5.6 Power 32. ANS: A PTS: 1 DIF: 3 TOP: 5.6 Power 33. ANS: C PTS: 1 DIF: 2 TOP: 5.6 Power 34. ANS: C PTS: 1 DIF: 2 TOP: 5.6 Power 35. ANS: C PTS: 1 DIF: 1 TOP: 5.7 Work Done by a Varying Force 36. ANS: A PTS: 1 DIF: 2 TOP: 5.7 Work Done by a Varying Force 1
37. ANS: C PTS: 1 DIF: 3 TOP: 5.7 Work Done by a Varying Force 38. ANS: C PTS: 1 DIF: 3 TOP: 5.7 Work Done by a Varying Force 39. ANS: D PTS: 1 DIF: 1 TOP: 5.1 Work 40. ANS: C PTS: 1 DIF: 1 2