1.1. A ball falls to the ground from a height h and bounces to height h¢. Momentum is
conserved in the ball-earth system
A. no matter what height h¢it reaches. B. only if h¢ < h.
C.only if h¢ = h. D. only if h¢ > h.
2. If you know the impulse that has acted on a body of mass m you can calculate
A. its initial velocity. B. its final velocity. C. its final momentum.
D. the change in its velocity. E. its acceleration during the impulse.
3. Two cars start at the same point, but in opposite directions on a circular path of radius
R, each at a speed v. While each car travels a distance less than 
, one quarter circle, the center of mass of the two cars
A. remains at the initial point. B. remains at the center of the circle.
C.travels along a diameter of the circle at speed v¢ < v.
D. travels along the diameter of the circle at speed v¢ = v.
E. travels along the diameter of the circle at speed v¢ > v.
4. Two bodies with a masses m1 and m2 are both moving east with velocities of
magnitudes v1 and v2, respectively. Note that v1 < v2. The magnitude of the velocity of the center of mass of this system of two bodies is
A. less than v1. B. equal to v1. C. equal to the average of v1 and v2.
D. greater than v2. E.greater than v1and less than v2.
5. The center of mass and center of gravity of a body
A. always coincide B. sometime coincide C. never coincide
D. you cannot fool me--this question is irrelevant since the center of mass and
center of gravity are entirely two different things.
8. The amount of work required to stop a moving object is equal to the
A. (speed )2 of the object B. mass of the object times its acceleration
C. ½ times mass (speed)2 of the object D. potential energy of the object
9. A student lifts a box of fresh roses, which just arrived from Mexico, 1.5 m in 3.0 second. If she
lifts the box the same distance in 6.0 second, the work done by her is:
A. the same B. two times as great C. half as great D. one-fourth as great
10. A 30-kg child rides on a circus Ferris wheel that takes her around a vertical circular path with a radius of 20 m every 22 s. What is the magnitude of the resultant force on the child at the highest point on this trajectory?
A. 19 N B. 29 N C. 49 N D. 0.25 kN E. 0.76 kN
11. A book is placed on a chair. Then a videocassette is placed on the book. The floor exerts a
normal force :
A. on all three. B. only on the book. C. only on the chair.
D. upwards on the chair and downwards on the book.
E. only on the objects that you have defined to be part of the system.
12. The vector sum of three co-planar forces:
A. must be zero. B. must be perpendicular to one of the three.
C. must be parallel to one of the three. D. must be perpendicular to the plane.
E. may have any direction in the plane.
13. You have a machine that can accelerate pucks on frictionless ice. In time t the puck travels a distance x when force F is applied. If force 3F is applied, in time t, the distance the box travels is: A. x. B. (3/2)x C. 3x. D. (9/2)x. E. 9x.
14. A rock attached to a string swings in a vertical circle. At the highest point:
A. Two forces act on the rock, and their resultant is not zero.
B. Only one force acts on the rock.
C. Two forces act on the rock, and their resultant is zero.
D. Three forces act on the rock.
E. No forces act on the rock.
15. A split highway has a number of lanes for traffic. For traffic going in one direction, the radius for the inside of the curve is half the radius for the outside. One car, car A, travels on the inside while another car of equal mass, car B, travels at equal speed on the outside of the curve. Which statement about resultant forces on the cars is correct?
A. The force on A is half the force on B. B. The force on B is half the force on A.
C. The force on A is four times the force on B. D. The force on B is four times the force on A.
16. A student is sitting on the right side of a school bus when it makes a right turn. We know that a force of gravity acts downwards and a normal force from the seat acts upwards. If the student stays in place when the bus turns, we also know that there must be:
A. no other force on the student.
B. a force parallel to the seat directed forward on the student.
C. a force parallel to the seat directed to the left on the student.
D. a force parallel to the seat directed to the right on the student.
E. a force parallel to the seat in a direction between forward and left on the student.
17. When a certain rubber band is stretched a distance x,it exerts a restoring force of magnitude
F = Ax, where A is a constant whose value depends on the stiffness of the rubber band. The work done by a student in stretching this rubber band from x = 0 to x = L is:
A. AL2 B. 2 AL2 C. ½ AL2 D. A/L2 E. 2 L2
18. The tension in a string from which a 4.0-kg object is suspended in an elevator is equal to 44 N.
What is the acceleration of the elevator?
A. 11 m/s2 upward B. 1.2 m/s2 upward C. 1.2 m/s2 downward D. 10 m/s2upward
19. A particle is acted upon by only two forces, one conservative and one nonconservative, as it moves from point A to point B. The kinetic energies of the particle at points A and B are equal if: A. the sum of the works of the two forces is zero.
B. the work of the conservative force is zero.
D. the work of the non-conservative force is zero
B. the work of the conservative force is equal to the work of the non-conservative force.
E. None of the above.
20. Two eggs of equal mass are thrown at a blanket with equal velocity. Egg A hits the wall instead but egg B hits the blanket. Compare the work done on the eggs in stopping them:
A. More work was done on A than on B. B. More work was done on B than on A.
C. The amount of work is the same for both.
D. It is meaningless to compare the amount of work because the forces were so different.
E. Work was done on B, but no work was done on A because the wall did not move.
21. In a contest, two tractors pull two identical blocks of stone the same distance over identical surfaces. However, block A is moving twice as fast as block B when it crosses the finish line. Which statement is correct?
A. Block A has twice as much kinetic energy as block B.
B. Block B has lost twice as much kinetic energy to friction as block A.
C. Block B has lost twice as much kinetic energy as block A.
D. Both blocks have had equal losses of energy to friction.
E. No energy is lost to friction because the ground has no displacement.
22. The same constant force is used to accelerate two carts of the same mass on frictionless tracks. The force is applied to cart A twice as long as it is applied to cart B. The work the force does on A is WA; that on B is WB. Which statement is correct?
A. WA = WB. B. WA = WB. C. WA = 2 WB. D. WA = 4 WB. E. WB = 2WA.
23. A hole Is drilled to the center of the Earth and a stone is dropped into it. When the stone is at the
Earth’s center, compared with the value at the Earth’s surface
A. its mass and weight are both changed
B. its mass and weight are both zero
C. its mass is unchanged and its weight is zero
D. its mass is unchanged and its weight approaches infinity its mass is unchanged and its
weight is indeterminable.
24. The horizontal surface shown on which the block slides is frictionless. If F = 20 N and
M = 5.0 kg, what is the magnitude of the resulting acceleration of the block?
A. 5.3 m/s2 B. 6.2 m/s2 C. 7.5 m/s2 D. 4.7 m/s2 E. 3.2 m/s2
25. The tension in a string from which a 4.0-kg object is suspended in an elevator is equal to 44 N.
What is the acceleration of the elevator?
A. 11 m/s2 upward B. 1.2 m/s2 upward C. 1.2 m/s2 downward D. 10 m/s2upward
26. A 2.5-kg object falls vertically downward in a viscous medium at a constant speed of
2.5 m/s. How much work is done by the viscous force on the object as it falls 80 cm?
A. +2.0 J B. +20 J C. –2.0 J D. –20 J E. + 40 J
27. A book is placed on a chair. Then a videocassette is placed on the book. The floor exerts a normal force : A. on all three. B. only on the book. C. only on the chair.
D. upwards on the chair and downwards on the book.
28. A constant force is applied to a body that is already moving. The force is directed at an angle of 60 degrees to the direction of the body's velocity. What is most likely to happen is that:
A. the body will stop moving.
B. the body will move in the direction of the force.
C. the body's velocity will increase in magnitude but not change direction.
D. the body will gradually change direction more and more toward that of the force while speeding up.
E. the body will first stop moving and then move in the direction of the force.
29. Which one of the following is true concerning momentum?
A. Momentum is a force B. Momentum is not a vector quantity
C. The SI unit of momentum is kg m2/s D. Momentum of an object is always positive
E. Momentum and impulse are measured in the same units.
30. A 0.1-kg ball is dropped straight down onto a hard horizontal floor and bounces straight up.
Its speed just before and just after impact with the floor is 10 m/s. Determine the magnitude of the
impulse delivered to the floor by the ball. A. zero Ns B. 1.0 Ns C. 2.0 Ns D. 10 Ns