PHYS 244 Exam 2 Review Questions

68) Jennifer hits a stationary 0.20-kg ball, and it leaves her racket at 40 m/s. Time-lapse photography shows that the ball was in contact with the racket for 40 ms. (a) What average force did the ball exert on the racket? (b) What is the ratio of this force to the weight of the ball?

(a) 0.20 kN (b) 100

82) In a police rifle test, a 15-g bullet traveling 213 m/s in a vertical direction suddenly buries itself in a 2.4-kg block of wood at rest directly above it. As a result, the bullet-block combination moves vertically upward. (a) Determine the velocity of the bullet-block combination just after the impact. (b) Determine the maximum height reached by the bullet/block combination. (c) Is kinetic energy conserved in this collision?

(a) 1.3 m/s (b) 0.089 m (c) No, this is an inelastic collision.

86) A car is traveling along a freeway at 65 mph. What is the linear speed, relative to the highway, of each of the following points on one of its tires? (a) the highest point on the tire (b) the lowest point on a tire (c) the center of the tire

(a) 130 mph (b) 0 mps (c) 65 mph

22) A small 175-g ball on the end of a light string is revolving uniformly on a frictionless surface in a horizontal circle of diameter 1.0 m. The ball makes 2.0 revolutions every 1.0 s. (a) What are the magnitude and direction of the acceleration of the ball? (b) Find the tension in the string.

(a) 79.0 m/s2 toward the center of the circle (b) 13.8 N

60) In a police ballistics test, 2.00-g bullet traveling at 700 m/s suddenly hits and becomes embedded in a stationary 5.00-kg wood block. What is the speed of the block immediately after the bullet has stopped moving relative to the block?

0.280 m/s

29) A very dense 1500-kg point mass (A) and a dense 1200-kg point mass (B) are held in place 1.00 m apart on a frictionless table. A third point mass is placed between the other two at a point that is 20.0 cm from B along the line connecting A and B. When the third mass is suddenly released, find the magnitude and direction (toward A or toward B) of its initial acceleration. (G = 6.67 × 10-11 N ∙ m2/kg2)

1.8 × 10-6 m/s2, toward B

82) A car (of mass 1500 kg) and a small truck (of mass 2000 kg) collide suddenly at right angles at an icy intersection. The car was originally traveling eastward at 20.0 m/s and the truck was traveling northward at 20.0 m/s just before the collision took place. What is the speed of the combined wreck just after the collision if the vehicles become enmeshed?

14.3 m/s

69) A 0.17-kg baseball is thrown with a speed of 38 m/s and it is hit straight back toward the pitcher with a speed of 62 m/s. What is the magnitude of the impulse exerted upon the ball by the bat?

17 N ∙ s

27) What is the magnitude of the gravitational force that two small 7.00-kg balls exert on each other when they are 35.0 cm apart? (G = 6.67 × 10-11 N ∙ m2/kg2)

2.67 × 10-8 N

18) A Ferris wheel has radius 5.0 m and makes one revolution every 8.0 s with uniform rotation. A person who normally weighs 670 N is sitting on one of the benches attached at the rim of the wheel. What is the apparent weight (the normal force exerted on her by the bench) of the person as she passes through the highest point of her motion?

460 N

67) A batter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the ball leaves the bat at 40 m/s in the reverse of its original direction. The ball remains in contact with the bat for 2.0 ms. What is the magnitude of the average force exerted by the bat on the ball?

4900N

81) An 80-kg man is skating northward and happens to suddenly collide with a 20-kg boy who is ice skating toward the east. Immediately after the collision, the man and boy are seen to be moving together at 2.5 m/s in a direction 60° north of east. How fast was the boy moving just before the collision?

6.3 m/s

28) Two identical tiny balls of highly compressed matter are 1.50 m apart. When released in an orbiting space station, they accelerate toward each other at 2.00 cm/s2. What is the mass of each of them? (G = 6.67 × 10-11 N ∙ m2/kg2)

6.75 × 108 kg

71) A 475-gram ball is traveling horizontally at 12.0 m/s to the left when it is suddenly struck horizontally by a bat, causing it to reverse direction and initially travel at 8.50 m/s to the right. If the bat produced an average force of 1275 N on the ball, for how long (in milliseconds) was it in contact with the ball?

7.64 ms

62) An empty train car of mass 2.0 x 104 kg coasts along at 10 m/s. A 3000-kg boulder is suddenly dropped vertically into the car. Find the speed of the car immediately after the boulder is dropped in

8.7 m/s

12) completely upside down. If the radius of the loop is with what minimum speed must the car traverse the loop so that the rider does not fall out while upside down at the top? Assume the rider is not strapped to the car. A) 11.4 m/s B) 12.5 m/s C) 10.1 m/s D) 14.9 m/s

A

13) A 1000-kg car is moving at 30 m/s around a horizontal unbanked curve whose diameter is 0.20 km. What is the magnitude of the friction force required to keep the car from sliding? A) 9000 N B) 9800 N C) 300 N D) 900 N E) 3000 N

A

14) The curved section of a horizontal highway is a circular unbanked arc of radius 740 m. If the coefficient of static friction between this roadway and typical tires is 0.40, what would be the maximum safe driving speed for this horizontal curved section of highway? A) 54 m/s B) 52 m/s C) 50 m/s D) 48 m/s E) 46 m/s

A

20) Pulling out of a dive, the pilot of an airplane guides his plane into a vertical circle with a radius of 600 m. At the bottom of the dive, the speed of the airplane is 150 m/s. What is the apparent weight of the 70-kg pilot at that point? A) 3300 N B) 690 N C) 2600 N D) 490 N E) 1400 N

A

21) Pulling out of a dive, the pilot of an airplane guides his plane into a vertical circle. At the bottom of the dive, the speed of the airplane is 320 m/s. What is the smallest radius allowable for the vertical circle if the pilot's apparent weight is not to exceed 7.0 times his true weight? A) 1700 m B) 1500 m C) 2200 m D) 230 m E) 42 m

A

26) What is the gravitational force acting on a 59-kg person due to another 59-kg person standing 2.0 m away? We can model each person as a small sphere. (G = 6.67 × 10-11 N ∙ m2/kg2) A) 5.8 × 10-8 N B) 8.5 × 103 N C) 1.2 × 10-7 N D) 9.8 × 10-10 N E) 2.0 × 10-9 N

A

30) A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which one of these objects experiences the greater momentum change? A) the ball B) the clay C) Both of them experience the same non-zero momentum change. D) Both of them experience zero momentum change.

A

40) In an inelastic collision involving an isolated system, the final total momentum is A) exactly the same as the initial momentum. B) more than the initial momentum. C) less than the initial momentum.

A

43) In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is PICTURE A) perfectly elastic. B) partially inelastic. C) completely inelastic. D) characterized by an increase in kinetic energy. E) not possible because momentum is not conserved.

A

49) A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. As a result of this bounce, which of the following quantities of the ball are conserved? (There could be more than one correct choice.) A) the kinetic energy of the ball B) the momentum of the ball C) both the momentum and the kinetic energy of the ball D) None of the above quantities are conserved.

A

65) In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges? A) 1.50 m/s B) 2.97 m/s C) 3.00 m/s D) 273 m/s

A

72) A block of mass m = 34 kg and speed V is behind a block of mass M = 81 kg and speed of 0.05m/s as shown in the figure. The surface is frictionless and the blocks collide and couple. After the collision, the blocks have a common speed of What is the magnitude of the impulse on the 34-kg block due to the collision? PICTURE A) 32 N ∙ s B) 14 N ∙ s C) 41 N ∙ s D) 57 N ∙ s E) 73 N ∙ s

A

74) A block of mass m = 5.6 kg, moving on a frictionless surface with a velocity of to the right, collides with a block of mass M at rest, as shown in the figure. After the collision, the 5.6-kg block recoils with a velocity of Vf=0.7m/s to the left. If the blocks are in contact for 0.20 s, what is the magnitude of the average force on the 5.6-kg block, while the two blocks are in contact? PICTURE A) 202 N B) 192 N C) 182 N D) 0 N E) 0 N

A

78) A block of mass m = 4.4 kg, moving on frictionless surface with a speed makes a sudden perfectly elastic collision with a second block of mass M, as shown in the figure. The second block is originally at rest. Just after the collision, the 4.4-kg block recoils with a speed of What is the mass M of the second block? PICTURE A) 7.7 kg B) 0 kg C) 0 kg D) 0 kg E) 0 kg

A

79) A block of mass m = 3.6 kg, moving on a frictionless surface with a speed makes a sudden perfectly elastic collision with a stationary block of mass M, as shown in the figure. Just after the collision, the 3.6-kg block recoils with a speed of What is the speed V of the other block? A) 6.6 m/s B) 8.0 m/s C) 9.3 m/s D) 10.7 m/s E) 12.0 m/s

A

89) Consider a solid uniform sphere of radius R and mass M rolling without slipping. Which form of its kinetic energy is larger, translational or rotational? A) Translational kinetic energy is larger. B) Rotational kinetic energy is larger. C) Both are equal. D) You need to know the speed of the sphere to tell.

A

9) If you stood on a planet having a mass four times that of Earth's mass, and a radius two times that of Earth's radius, you would weigh A) the same as you do on Earth. B) two times more than you do on Earth. C) two times less than you do on Earth. D) four times more than you do on Earth.

A

94) Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force has a greater magnitude? A) the first force (at the midpoint) B) the second force (at the doorknob) C) The two forces are equal.

A

95) As shown in the figure, a given force is applied to a rod in several different ways. In which case is the torque about the pivot P due to this force the greatest? PICTURE A) 1 B) 2 C) 3 D) 4 E) 5

A

A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at in the same direction. If the second car has a mass of and a speed of right after the collision, what is the velocity of the first car after this sudden collision? A) 14.0 m/s B) 18.2 m/s C) 24.2 m/s D) -14.0 m/s

A

A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall horizontally with a speed of and it bounces back with this same speed. The ball is in contact with the wall 0.05s. What is the magnitude of the average force exerted on the wall by the ball? A) 800 N B) 400 N C) 55,000 N D) 27,500 N E) 13,750 N

A

When a car goes around a banked circular curve at the proper speed for the banking angle, what force cause it to follow the circular path? A) the normal force from the road B) the friction force from the road C) gravity D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

A

84) When a rigid object rotates about a fixed axis, what is true about all the points in the object? (There could be more than one correct choice.) A) They all have the same angular speed. B) They all have the same tangential speed. C) They all have the same angular acceleration. D) They all have the same tangential acceleration. E) They all have the same radial acceleration.

A,C

41) A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of the following statements is true? (There could be more than one correct choice.) A) The magnitude of the change of velocity the 5-kg ball experiences is greater than that of the 10-kg ball. B) The magnitude of the change of velocity the 5-kg ball experiences is less than that of the 10- kg ball. C) The magnitude of the change of velocity the 5-kg ball experiences is equal to that of the 10-kg ball. D) The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of the change of momentum of the 10-kg ball. E) Both balls lose all their momentum since the collision is inelastic.

A,D

80) In a perfectly elastic collision, a 400-g ball moving toward the east at 3.7 m/s suddenly collides head-on with a 200 g ball sitting at rest. (a) Determine the velocity of the first ball just after the collision. (b) Determine the velocity of the second ball just after the collision. (c) Is kinetic energy conserved in this collision? How do you know?

Answer: (a) 1.2 m/s toward the east (b) 4.9 m/s toward the east (c) Yes, it is an elastic collision.

25) A curved portion of highway has a radius of curvature of 65 m. As a highway engineer, you want to bank this curve at the proper angle for a steady speed of 22 m/s. (a) What banking angle should you specify for this curve? (b) At the proper banking angle, what normal force and what friction force does the highway exert on a 750-kg car going around the curve at the proper speed?

Answer: (a) 37° (b) 9200 N (normal force), 0 N (friction)

75) A force of 5.3 N is needed to hold on to an umbrella in a strong wind. If the air molecules each have a mass of 4.7 ×10-26 kg, and each one strikes the umbrella (without rebounding) with a speed of 2.0 m/s in the same direction, how many atoms strike the umbrella each second? Assume that the wind blows horizontally so that the gravity can be neglected.

Answer: 5.6 ×1025 per second

83) Three balls are moving along a straight line having the instantaneous positions shown in the figure. At that instant, find the location and velocity of the center of mass (or center of gravity) of this system. PICTURE

Answer: 7.00 m to the right of the 2.00 kg ball, 1.11 m/s to the right

76) A 2200-kg auto moving northward at 12.0 m/s runs into a 3800-kg truck which is also moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving just after the collision?

Answer: 7.57 m/s

77) A 2.0-kg mass moving at 5.0 m/s suddenly collides head-on with a 3.0-kg mass at rest. If the collision is perfectly inelastic, what is the speed of the masses just after the collision? A) 10 m/s B) 2.5 m/s C) 2.0 m/s D) 0 m/s, since the collision is inelastic

Answer: C

11) The reason an astronaut in an earth satellite feels weightless is that A) the astronaut is beyond the range of the earth's gravity. B) the astronaut is falling. C) the astronaut is at a point in space where the effects of the moon's gravity and the earth's gravity cancel. D) this is a psychological effect associated with rapid motion. E) the astronaut's acceleration is zero.

B

2) When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path? A) the normal force from the road B) the friction force from the road C) gravity D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

B

33) Two friends are standing on opposite ends of a canoe that is initially at rest with respect to a frictionless lake. The person in the front throws a very massive ball toward the back, and the person in the back catches it. After the ball is caught, the canoe is A) moving backward. B) stationary. C) moving forward.

B

34) You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You have two choices about what to do with the ball: either catch the ball or deflect it back toward your friend with the same speed as it was originally thrown. Which choice should you make in order to maximize your speed on the skateboard? A) Catch the ball. B) Deflect the ball back. C) Your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball.

B

36) A rocket explodes into two fragments, one 25 times heavier than the other. The magnitude of the momentum change of the lighter fragment is A) 25 times as great as the momentum change of the heavier fragment. B) The same as the momentum change of the heavier fragment. C) 1/25 as great as the momentum change of the heavier fragment. D) 5 times as great as the momentum change of the heavier fragment. E) 1/4 as great as the momentum change of the heavier fragment.

B

42) In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball had originally. Both balls have the same mass. This type of collision is A) somewhat inelastic. B) elastic. C) completely inelastic.

B

48) A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system A) is the same as before. B) is half as much as before. C) is one third as much as before. D) is one fourth as much as before. E) is one quarter as much as before

B

5) If you swing a bucket of water fast enough in a vertical circle, at the highest point the water does not spill out. This happens because an outward force balances the pull of gravity on the water. A) True B) False

B

63) Two ice skaters suddenly push off against one another starting from a stationary position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire relative to the ice? A) 0.50 m/s B) 0.28 m/s C) 0.38 m/s D) 0.75 m/s E) 0.00 m/s

B

66) Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer space. They suddenly push each other apart. How far has the heavier astronaut moved when the lighter astronaut has moved 12 m? A) 16 m B) 9.0 m C) 21 m D) 7.0 m E) 12 m

B

87) The figure shows scale drawings of four objects, each of the same mass and uniform thickness, with the mass distributed uniformly. Which one has the greatest moment of inertia when rotated about an axis perpendicular to the plane of the drawing at point P? PICTURE A) A B) B C) C D) D E) The moment of inertia is the same for all of these objects.

B

90) A disk and a hoop of the same mass and radius are released at the same time at the top of an inclined plane. If both are uniform, which one reaches the bottom of the incline first if there is no slipping? A) The hoop B) The disk C) Both reach the bottom at the same time.

B

92) Suppose a solid uniform sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The angular velocity of the sphere at the bottom of the incline depends on A) the mass of the sphere. B) the radius of the sphere. C) both the mass and the radius of the sphere. D) neither the mass nor the radius of the sphere.

B

93) A uniform ball is released from rest on a no-slip surface, as shown in the figure. After reaching its lowest point, the ball begins to rise again, this time on a frictionless surface. When the ball reaches its maximum height on the frictionless surface, it is A) higher than when it was released. B) lower than when it was released. C) at the same height from which it was released. D) It is impossible to tell without knowing the mass of the ball. E) It is impossible to tell without knowing the radius of the ball.

B

97) The rotating systems shown in the figure differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest, A) the block at the left lands first. B) the block at the right lands first. C) both blocks land at the same time.

B

85) Two children, Ahmed and Jacques, ride on a merry-go-round. Ahmed is at a greater distance from the axis of rotation than Jacques. Which of the following are true statements? (There could be more than one correct choice.) A) Jacques has a greater angular speed than Ahmed. B) Jacques and Ahmed have the same angular speed. C) Jacques has a smaller angular speed than Ahmed. D) Ahmed has a greater tangential speed than Jacques. E) Jacques and Ahmed have the same tangential speed

B,D

1) You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it A) moves along a straight-line path away from the center of the circle. B) moves along a straight-line path toward the center of the circle. C) moves along a straight-line path in its original direction. D) continues to follow a circular path, but with a radius larger than the original radius. E) moves along a path that is neither straight nor circular.

C

15) A 250-kg motorcycle goes around an unbanked turn of radius 13.7 m at a steady 96.5 km/h. What is the magnitude of the net force on the motorcycle? A) 719 N B) 2.95 × 103 N C) 1.31 × 104 N D) 4.31 × 104 N

C

35) A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the momentum change during the collision is correct? (There could be more than one correct choice.) A) The truck experiences the greater magnitude momentum change. B) The small car experiences the greater magnitude momentum change. C) The small car and the truck experience the same magnitude momentum change. D) The magnitude of the momentum change experienced by each one is inversely proportional to its mass. E) The magnitude of the momentum change experienced by each one is directly proportional to its mass.

C

39) Identical forces act for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is A) smaller than the magnitude of the change in momentum of the larger mass, but not zero. B) larger than the magnitude of the change in momentum of the larger mass. C) exactly equal to the magnitude of the change in momentum of the larger mass. D) zero. E) There is not enough information to answer the question

C

4) When an object moves in uniform circular motion, the direction of its acceleration is A) in the same direction as its velocity vector. B) in the opposite direction of its velocity vector. C) is directed toward the center of its circular path. D) is directed away from the center of its circular path. E) depends on the speed of the object.

C

45) In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is PICTURE A) perfectly elastic. B) partially inelastic. C) completely inelastic. D) characterized by an increase in kinetic energy. E) not possible because momentum is not conserved.

C

46) A 2.0-kg ball moving eastward at 3.0 m/s suddenly collides with and sticks to a 4.0-kg ball moving northward at 2.0 m/s. What is the magnitude of the momentum of this system just after the collision? A) 14 kg ∙ m/s B) 2.0 kg ∙ m/s C) 10 kg ∙ m/s D) 6.0 kg ∙ m/s E) 8.0 kg ∙ m/s

C

50) On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to the table. The puck compresses the spring by 15 cm before coming to rest. During the compression process, which quantities are conserved? A) only the momentum of the puck B) only the kinetic energy of the puck C) only the mechanical energy (kinetic plus potential) of the puck D) the momentum and the mechanical energy of the puck E) the momentum and the kinetic energy of the puck

C

7) Two cars go around a banked curve at the proper speed for the banking angle. One car has tires with excellent traction, while the other car has bald slippery tires. Which of these cars is more likely to slide on the pavement as it goes around the curve? A) the car with the new tires B) the car with the bald tires C) Neither car will slide. D) It depends on if the pavement is wet or dry

C

88) Consider a uniform hoop of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or its rotational kinetic energy? A) Translational kinetic energy is larger. B) Rotational kinetic energy is larger. C) Both are equal. D) You need to know the speed of the hoop to tell.

C

96) Five forces act on a rod that is free to pivot at point P, as shown in the figure. Which of these forces is producing a counter-clockwise torque about point P? (There could be more than one correct choice.) PICTURE A) force A B) force B C) force C D) force D E) force E

C

In a collision between two unequal masses, which mass receives a greater magnitude impulse? A) the larger mass B) the smaller mass C) They receive equal impulses.

C

37) Which of the following quantities are units of impulse? (There could be more than one correct choice.) A) N ∙ m B) kg ∙ s/m C) kg ∙ m/s D) N ∙ s E) kg ∙ m2/s2

C,D

16) A jet plane flying 600 m/s experiences an acceleration of 4.0 g when pulling out of a circular dive. What is the radius of curvature of the circular part of the path in which the plane is flying? A) 640 m B) 1200 m C) 7100 m D) 9200 m

D

3) A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road? A) tangent to the curve in the forward direction B) tangent to the curve opposite to the direction of the car's motion C) perpendicular to the curve outward D) perpendicular to the curve inward E) There is no friction on the car because its speed is constant.

D

47) An egg falls from a bird's nest in a tree and feels no effects due to the air. As it falls, A) only its kinetic energy is conserved. B) only its momentum is conserved. C) both its kinetic energy and its momentum are conserved. D) only its mechanical energy is conserved. E) both its mechanical energy and its momentum are conserved.

D

52) Three objects are moving along a straight line as shown in the figure. Taking the positive direction to be to the right, what is the total momentum of this system? PICTURE A) +106 kg ∙ m/s B) -106 kg ∙ m/s C) +14.0 kg ∙ m/s D) -14.0 kg ∙ m/s E) 0.00 kg ∙ m/s

D

64) A dinner plate falls vertically to the floor and breaks up into three pieces, which slide horizontally along the floor. Immediately after the impact, a 200-g piece moves along the +x-axis with a speed of 2.00 m/s, a 235-g piece moves along the +y-axis with a speed of 1.50 m/s. The third piece has a mass of 100 g. What is the speed of the third piece? A) 2.51 m/s B) 2.57 m/s C) 3.50 m/s D) 5.33 m/s E) 6.83 m/s

D

8) A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth's gravity? A) when it gets above the atmosphere B) when it is half-way there C) when it is closer to the Moon than it is to Earth D) It is never beyond the pull of Earth's gravity.

D

83) As shown in the figure, a bullet of mass 0.010 kg moving horizontally suddenly strikes a block of wood of mass 1.5 kg that is suspended as a pendulum. The bullet lodges in the wood, and together they swing upward a vertical distance of 0.40 m. The length of the string is 2.0 m. What was the speed of the bullet just before it struck the wooden block? PICTURE A) 67 m/s B) 250 m/s C) 370 m/s D) 420 m/s E) 650 m/s

D

91) Suppose a uniform solid sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The linear velocity of the sphere at the bottom of the incline depends on A) the mass of the sphere. B) the radius of the sphere. C) both the mass and the radius of the sphere. D) neither the mass nor the radius of the sphere.

D

98) A person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms, A) her moment of inertia decreases and her angular speed increases. B) her moment of inertia decreases and her angular speed decreases. C) her moment of inertia increases and her angular speed increases. D) her moment of inertia increases and her angular speed decreases. E) her moment of inertia increases and her angular speed remains the same.

D

10) A piece of space debris is released from rest at an altitude that is two earth radii from the center of the earth. Compared to its weight on Earth, the weight of this debris is A) zero. B) the same as on the surface of the earth. C) one-half of its weight on the surface of the earth. D) one-third of its weight on the surface of the earth. E) one-quarter of its weight on the surface of the earth

E

44) In the figure showing an isolated system, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is PICTURE A) perfectly elastic. B) partially inelastic. C) completely inelastic. D) characterized by an increase in kinetic energy. E) not possible because momentum is not conserved.

E

73) A batter hits a foul ball. The 0.14-kg baseball that was approaching him at 40 m/s leaves the bat at 30 m/s in a direction perpendicular to the line between the batter and the pitcher. What is the magnitude of the impulse delivered to the baseball? A) 9.8 N ∙ s B) 1.4 N ∙ s C) 3.5 N ∙ s D) 5.6 N ∙ s E) 7.0 N ∙ s

E

A 1000-kg car is slowly picking up speed as it goes around a horizontal unbanked curve whose radius is 100 m. The coefficient of static friction between the tires and the road is 0.35. At what speed will the car begin to skid sideways? A) 9.3 m/s B) 24 m/s C) 34 m/s D) 35 m/s E) 19 m/s

E

32) The momentum of an isolated system is conserved A) only in inelastic collisions. B) only in elastic collisions. C) in both elastic and inelastic collisions.

c

31) Which of the following quantities are units of momentum? (There could be more than one correct choice.) A) N ∙ m B) kg ∙ s/m C) kg ∙ m/s D) N ∙ s E) kg ∙ m2/s2

c,d