5. Two ropes are attached to a 40-kg object. The first rope applies a force of 25 N and the second, 40 N. If the two ropes are perpendicular to each other, what is the resultant acceleration of the object?
a. 1.2 m/s2
b. 3.0 m/s2
c. 25 m/s2
d. 47 m/s2

8. Two blocks, joined by a string, have masses of 6.0 and 9.0 kg. They rest on a frictionless horizontal surface. A 2nd string, attached only to the 9-kg block, has horizontal force = 30 N applied to it. Both blocks accelerate. Find the tension in the string between the blocks.
a. 18 N
b. 28 N
c. 12 N
d. 15 N

15. A cart of weight 20 N is accelerated across a level surface at 0.15 m/s2. What net force acts on the wagon? (g = 9.8 m/s2)
a. 0.92 N
b. 0.31 N
c. 3.0 N
d. 4.5 N

16. An airplane of mass 1.2 ´ 104 kg tows a glider of mass 0.6 ´ 104 kg. The airplane propellers provide a net forward thrust of 3.6 ´ 104 N. What is the glider's acceleration?
a. 2.0 m/s2
b. 3.0 m/s2
c. 6.0 m/s2
d. 9.8 m/s2

23. A 100-kg box is placed on a ramp. As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15°. What is the coefficient of static friction between box and ramp?
a. 0.15
b. 0.27
c. 0.77
d. 0.95

24. A 300-kg crate is placed on an adjustable inclined plane. As one end of the incline is raised, the crate begins to move downward. If the crate slides down the plane with an acceleration of 0.70 m/s2 when the incline angle is 25°, what is the coefficient of kinetic friction between ramp and crate? (g = 9.8 m/s2)
a. 0.47
b. 0.42
c. 0.39
d. 0.12

25. A 250-kg crate is placed on an adjustable inclined plane. If the crate slides down the incline with an acceleration of 0.70 m/s2 when the incline angle is 25°, then what should the incline angle be for the crate to slide down the plane at constant speed? (g = 9.8 m/s2)
a. 12°
b. 21°
c. 25°
d. 29°

29. An elevator weighing 20 000 N is supported by a steel cable. What is the tension in the cable when the elevator is being accelerated upward at a rate of 3.00 m/s2? (g = 9.80 m/s2)
a. 13 900 N
b. 23 100 N
c. 20 000 N
d. 26 100 N

30. It is late and Carlos is sliding down a rope from his third floor window to meet his friend Juan. As he slides down the rope faster and faster, he becomes frightened and grabs harder on the rope, increasing the tension in the rope. As soon as the upward tension in the rope becomes equal to his weight:
a. Carlos will stop.
b. Carlos will slow down.
c. Carlos will continue down at a constant velocity.
d. the rope must break.

33. As I slide a box at constant speed up a frictionless slope, pulling parallel to the slope, the tension in the rope will be:
a. greater than the tension would be if the box were stationary.
b. greater than the weight of the box.
c. equal to the weight of the box.
d. less than the weight of the box.

34. A boxcar of mass 200 tons at rest becomes uncoupled on a 2.5° grade. If the track is considered to be frictionless, what speed does the boxcar have after 10 seconds?

a. 0.37 m/s
b. 0.59 m/s
c. 1.3 m/s
d. 4.3 m/s

38. There are six books in a stack, each with a weight of 5.0 N. The coefficient of friction between all the books is 0.20 as is the coefficient between the table and the bottom book. With what horizontal force must I push to start sliding the top five books off the bottom one?
a. 1.0 N
b. 5.0 N
c. 3.0 N
d. 7.0 N

40. As a 3.0-kg bucket is being lowered into a 10-m-deep well, starting from the top, the tension in the rope is 9.8 N. The acceleration of the bucket will be:
a. 6.5 m/s2 downward
b. 9.8 m/s2 downward
c. zero
d. 3.3 m/s2 upward

59. A karate master strikes a board with an initial velocity of 10.0 m/s, decreasing to 1.0 m/s as his hand passes through the board. If the time of contact with the board is 0.002 0 s, and the mass of the coordinated hand and arm is 1.0 kg, what is the force exerted on the board?
a. 1 000 N
b. 1 800 N
c. 2 700 N
d. 4 500 N

72. A block is launched up an incline plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3. The time for the trip up the plane
a. is the same as the time for the trip down.
b. is more than the time for the trip down.
c. is less than the time for the trip down.
d. cannot be found compared without knowing the angle of inclination.

16. When an object is dropped from a tower, what is the effect of the air resistance as it falls?
a. does positive work
b. increases the object's kinetic energy
c. increases the object's potential energy
d. None of the above choices are valid.

27. 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

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

38. I use a rope 2.00 m long to swing a 10.0-kg weight around my head. The tension in the rope is 20.0 N. In half a revolution how much work is done by the rope on the weight?
a. 40.0 J
b. 126 J
c. 251 J
d. 0

39. The work done by static friction can be:
a. positive
b. negative
c. zero
d. any of the above

41. 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

42. If both mass and velocity of a ball are tripled, the kinetic energy is increased by a factor of:
a. 3
b. 6
c. 9
d. 27

43. A 2.00-kg ball has zero kinetic and potential energy. Ernie drops the ball into a 10.0-m-deep well. Just before the ball hits the bottom, the sum of its kinetic and potential energy is:
a. zero
b. 196 J
c. -196 J
d. 392 J

45. Two blocks are released from the top of a building. One falls straight down while the other slides down a smooth ramp. If all friction is ignored, which one is moving faster when it reaches the bottom?
a. The block that went straight down.
b. The block that went down the ramp.
c. They both will have the same speed.
d. Insufficient information to work the problem.

48. 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

52. Yuri, a Russian weightlifter, is able to lift 250 kg 2.00 m in 2.00 s. What is his power output?
a. 500 W
b. 2.45 kW
c. 4.90 kW
d. 9.80 kW

61. 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 x 108 J
b. 1.6 x 1011 J
c. 6.4 x 1011 J
d. 0

3. A 75-kg swimmer dives horizontally off a 500-kg raft. If the diver's speed immediately after leaving the raft is 4 m/s, what is the corresponding raft speed?
a. 0.2 m/s
b. 0.5 m/s
c. 0.6 m/s
d. 4.0 m/s

5. During a snowball fight two balls with masses of 0.4 and 0.6 kg, respectively, are thrown in such a manner that they meet head on and combine to form a single mass. The magnitude of initial velocity for each is 15 m/s. What is the speed of the 1.0-kg mass immediately after collision?
a. zero
b. 3 m/s
c. 6 m/s
d. 9 m/s

9. A billiard ball collides in an elastic head on collision with a second stationary identical ball. After the collision which of the following conditions applies to the first ball?
a. maintains the same velocity as before
b. has one half its initial velocity
c. comes to rest
d. moves in the opposite direction

10. A billiard ball collides in an elastic head on collision with a second identical ball. What is the kinetic energy of the system after the collision compared to that before collision?
a. the same as
b. one fourth
c. twice
d. four times

11. In a two body collision, if the momentum of the system is conserved, then which of the following best describes the kinetic energy after the collision?
a. must be less
b. must also be conserved
c. may also be conserved
d. is doubled in value

33. A uranium nucleus (mass 238 units) at rest decays into a helium nucleus (mass 4.0 units) and a thorium nucleus (mass 234 units). If the speed of the helium nucleus is 6.0 ´ 105 m/s, what is the speed of the thorium nucleus?
a. 1.0 x 104 m/s
b. 3.0 ´ 104 m/s
c. 3.6 ´ 104 m/s
d. 4.1 ´ 104 m/s

35. If the momentum of an object is tripled, its kinetic energy will change by what factor?
a. zero
b. one third
c. three
d. nine

39. Two objects, one less massive than the other, collide elastically and bounce back after the collision. If the two originally had velocities that were equal in size but opposite in direction, then after the collision which one will be moving faster?
a. The less massive one.
b. The more massive one.
c. The speeds will be the same after the collision.
d. There is no way to be sure without the actual masses.

41. If a glass of water is on a table with a piece of paper under it, it is relatively easy to pull the paper out without disturbing the glass very much if the pull is done very quickly. This is because, with a quick pull:
a. the force on the glass will be less.
b. the momentum of the paper will be greater.
c. the time for the pull will be less.
d. the coefficient of kinetic friction will be less.

50. A tennis ball is held above and in contact with a basketball, and then both are simultaneously dropped. The tennis ball bounces off the basketball at a fairly high speed. This is because:
a. The basketball falls farther than the tennis ball.
b. The tennis ball is slightly shielded from the Earth's gravitational pull.
c. The massive basketball transfers momentum to the lighter tennis ball.
d. The tennis ball has a smaller radius.

56. Mitch throws a 100 g lump of clay at a 500-g target, which is at rest on a horizontal surface. After impact, the target, including the attached clay, slides 2.1 m before stopping. If the coefficient of friction is µ = 0.50, find the speed of the clay before impact.
a. 4.5 m/s
b. 12 m/s
c. 27 m/s
d. 36 m/s

59. Two identical 7-kg bowling balls roll toward each other. The one on the left is moving at +4 m/s while the one on the right is moving at -4 m/s. What is the velocity of each ball after they collide elastically?
a. Neither is moving.
b. -4 m/s, +4 m/s
c. +4 m/s, -4 m/s
d. -14 m/s, 14 m/s

62. A 5-kg object is moving to the right at 4 m/s and collides with another object moving to the left at 5 m/s. The objects collide and stick together. After the collision, the combined object
a. is moving to the right.
b. is moving to the left.
c. is at rest.
d. has less kinetic energy than the system had before the collision.

9. A 0.40-kg mass, attached to the end of a 0.75-m string, is whirled around in a circular horizontal path. If the maximum tension that the string can withstand is 450 N, then what maximum speed can the mass have if the string is not to break?
a. 370 m/s
b. 22 m/s
c. 19 m/s
d. 29 m/s

10. Two satellites are monitored as they orbit the Earth; satellite X is eight times as far from the Earth's center as is satellite Y. From Kepler's third law one may conclude that the period or revolution of X is what factor times that of Y?
a. 1/2
b. 2.0
c. 4.0
d. 22.6

16. At what location does an artificial Earth satellite in elliptical orbit have its greatest speed?
a. nearest the Earth
b. farthest from the Earth
c. between Earth and Moon
d. between Earth and Sun

18. Which of the following best describes the property of the period of orbital revolution for an Earth satellite?
a. greater when the orbital radius is smaller
b. greater when the orbital radius is larger
c. independent of the orbital radius
d. determined mainly by the satellite's mass

19. Of the nine known planets in our solar system, the innermost is Mercury. When compared to the other planets in the system, Mercury has the:
a. greatest centripetal acceleration.
b. greatest period of revolution.
c. smallest angular velocity.
d. smallest tangential velocity.

28. A 0.400-kg object is swung in a circular path and in a vertical plane on a 0.500-m-length string. If the angular speed at the bottom is 8.00 rad/s, what is the tension in the string when the object is at the bottom of the circle?
a. 5.60 N
b. 10.5 N
c. 16.7 N
d. 19.6 N

32. At what speed will a car round a 52-m-radius curve, banked at a 45 angle, if no friction is required between the road and tires to prevent the car from slipping? (g = 9.8 m/s2)
a. 27 m/s
b. 17 m/s
c. 23 m/s
d. 35 m/s

35. An object of mass 0.50 kg is transported to the surface of Planet X where the object's weight is measured to be 20 N. The radius of the planet is 4.0 106 m. What free fall acceleration will the 0.50-kg object experience when transported to a distance of 2.0 106 m from the surface of this planet?
a. 90 m/s2
b. 20 m/s2
c. 13 m/s2
d. 18 m/s2

39. Consider a point on a bicycle wheel as the wheel makes exactly four complete revolutions about a fixed axis. Compare the linear and angular displacement of the point.
a. Both are zero.
b. Only the angular displacement is zero.
c. Only the linear displacement is zero.
d. Neither is zero.

42. Consider a point on a bicycle tire that is momentarily in contact with the ground as the bicycle rolls across the ground with constant speed. The direction for the acceleration for this point at that moment is:
a. upward.
b. down toward the ground.
c. forward.
d. at that moment the acceleration is zero.

43. Consider a child who is swinging. As she reaches the lowest point in her swing:
a. the tension in the rope is equal to her weight.
b. the tension in the rope is equal to her mass times her acceleration.
c. her acceleration is downward at 9.8 m/s2.
d. none of the above.

44. An Earth satellite is orbiting at a distance from the Earth's surface equal to one Earth radius (4 000 miles). At this location, the acceleration due to gravity is what factor times the value of g at the Earth's surface?
a. There is no acceleration since the satellite is in orbit.
b. 2
c. 1/2
d. 1/4

48. Calculate the linear speed due to the Earth's rotation for a person at the equator of the Earth. The radius of the Earth is 6.40 106 m.
a. 74.0 m/s
b. 233 m/s
c. 465 m/s
d. 73.0 m/s

49. According to Kepler's second law, Halley's Comet circles the Sun in an elliptical path with the Sun at one focus of the ellipse. What is at the other focus of the ellipse?
a. nothing
b. the Earth
c. The comet itself passes through the other focus.
d. The tail of the comet stays at the other ellipse.

50. Somewhere between the Earth and the Moon is a point where the gravitational attraction of the Earth is canceled by the gravitational pull of the Moon. The mass of the Moon is 1/81 that of the Earth. How far from the center of the Earth is this point?
a. 8/9 the way to the Moon
b. 9/10 the way to the Moon
c. 3/4 the way to the Moon
d. 80/81 the way to the Moon

53. An airplane in a wide sweeping "outside" loop can create zero gees inside the aircraft cabin. What must be the radius of curvature of the flight path for an aircraft moving at 150 m/s to create a condition of "weightlessness" inside the aircraft?
a. 1 150 m
b. 1 800 m
c. 2 300 m
d. 3 600 m

57. The Earth is 93 million miles (mi) from the Sun and its period of revolution is 1 year = 3.15 107 s. What is the acceleration of the Earth in its orbit about the Sun?
a. 18.6 mi/s2
b. 9.3 10 3 mi/s2
c. 13.6 10 6 mi/s2
d. 3.7 10 6 mi/s2

61. In order for a satellite to be geosynchronous, its orbit must
a. go over the North and South Poles.
b. be over the equator.
c. be over a single longitude.
d. emit television signals.

62. An asteroid is in orbit at 4 times the earth's distance from the Sun. What is its period of revolution?
a. one fourth year
b. 4 years
c. 8 years
d. 16 years

64. At an altitude of 4 times the radius of the earth, the acceleration due to gravity is
a. g/2.
b. g/4.
c. g/16.
d. not given.

65. A wheel is rotated about a horizontal axle at a constant angular speed. Next it is rotated in the opposite direction with the same angular speed. The acceleration at a point on the top of the wheel in the second case as compared to the acceleration in the first case
a. is in the same direction.
b. is in the opposite direction.
c. is upward.
d. is tangential to the wheel.