Download TRUE/FALSE. Write `T` if the statement is true and

Exam
Name___________________________________
TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false.
1) Mass is a measure of how difficult it is to change the velocity of an object.
1)
2) Work is a vector quantity.
2)
False
3) The force of kinetic friction between two surfaces is independent of the area of contact between the
surfaces.
3)
4) The frictional force is a conservative force.
4)
False
5) Kinetic energy is proportional to speed.
5)
False
6) A particle that has zero momentum must also have zero kinetic energy.
6)
True
7) Any location can be chosen for potential energy equal to zero.
7)
True
8) When objects stick together after colliding, the collision is completely elastic.
8)
False
9) The banking angle for a properly banked curve does not depend on the mass of the car going over
it. True
9)
10) The force fo static friction between two surfaces is parallel to the surface of contact, and in in the
direction that opposes relative motion.
10)
11) The acceleration of an object does not have to be in the same direction as the net force applied to it.
11)
12) The mass of an object is fixed, but its weight varies from location to location.
12)
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
13) A constant net force acts on an object. Describe the motion of the object.
A) increasing acceleration.
B) zero acceleration.
C) constant non-zero velocity.
D) constant non-zero acceleration.XXX
E) decreasing acceleration.
13)
14) A truck is towing a car whose mass is one quarter that of the truck. The force exerted by the truck
on the car is 6000 N. The force exerted by the car on the truck is
A) 24000 N.
B) 6000 N.XXX
C) 12000 N.
D) 3000 N.
E) 1500 N.
14)
1
FIGURE 6-1
15) In Figure 6-1, the block of mass m is at rest on an inclined plane that makes an angle
horizontal. The force of static friction f must be such that
A) f > mg sin .
B) f > mg cos .
C) f = mg cos .
D) f > mg.
E) f = mg sin .XXX
with the
15)
FIGURE 6-5
16) Two masses, m1 and m2, are connected to each other as shown in Figure 6-5. Mass m1 slides
without friction on the table surface. Both masses have acceleration of magnitude a as shown. How
does the tension in the string compare to the weight, m2 g, of mass m2 ?
A) The tension is smaller than m2 g.XXX
B) The tension is equal to m2 g.
C) The tension is larger than m2 g.
D) It depends on m1 being smaller than m2 .
E) It depends on m1 being larger than m2 .
16)
17) A block of mass M slides down a frictionless plane inclined at an angle
normal reaction force exerted by the plane on the block is
A) Mg sin .
B) Mg.
C) Mg cos .XXX
D) Mg tan .
E) zero, since the plane is frictionless.
17)
2
with the horizontal. The
18) A net force of 125 N is applied to a certain object. As a result, the object accelerates with an
acceleration of 24.0 m/s 2 . The mass of the object is
A) 3000 kg.
B) 0.200 kg.
C) 144 kg.
D) 2880 kg.
E) 5.20 kg.XXX
18)
19) When a car goes around a curve, it has a tendency to skid outwards. Is the frictional force between
the tires and the ground that keeps the car from skidding kinetic or static?
A) staticXXX
B) kinetic
19)
20) A roller coaster car (mass = M) is on a track that forms a circular loop (radius = r) in the vertical
plane. If the car is to just maintain contact with the track at the top of the loop, what is the
minimum value for its speed at that point?
A) (0.5rg)1/2
B) (rg)1/2XXX
C) 2rg
D) (2rg)1/2
E) rg
20)
21) A net force of 450 N applied to a car results in the car accelerating at 0.360 m/s 2 . What is the mass
of the car?
A) 625 kg
B) 12300 kg
C) 1590 kg
D) 1250 kgXXX
E) 162 kg
21)
22) A 50.0-kg box is being pushed along a horizontal surface. The coefficient of kinetic friction
between the box and the ground is 0.350. What horizontal force must be exerted on the box for it to
accelerate at 1.20 m/s2 ?
A) 116 N
B) 60.0 N
C) 172 N
D) 491 N
E) 232 NXXX
22)
3
FIGURE 6-13
23) Refer to Figure 6-13. Block A has a mass of 3.00 kg, block B has a mass of 5.00 kg and block C has a
mass of 2.00 kg. The pulleys are ideal and there is no friction between block B and the table. What
is the acceleration of the masses?
A) 1.86 m/s 2
B) 2.94 m/s 2
C) 4.20 m/s 2
D) 4.71 m/s 2
E) 0.981 m/s2 XXX
23)
FIGURE 6-12
24) Two masses are connected by a string which goes over an ideal pulley as shown in Figure 6-12.
Block A has a mass of 3.0 kg and can slide along a smooth plane inclined 30° to the horizontal.
What is the mass of block B if the system is in equilibrium?
A) 1.5 kgXXX
B) 3.0 kg
C) 3.5 kg
D) 6.0 kg
E) 2.6 kg
24)
25) A 600-kg car is going over a curve with a radius of 120 m that is banked at an angle of 25° with a
speed of 30.0 m/s. The coefficient of static friction between the car and the road is 0.30. What is the
normal force exerted by the road on the car?
A) 5330 N
B) 3430 N
C) 7240 NXXX
D) 1590 N
E) 3620 N
25)
4
FIGURE 6-15
26) A 20.0-gram mass is attached to a 120 cm-long string as shown in Figure 6-15. It moves in a
horizontal circle with a constant speed of 1.50 m/s. What is the angle ?
A) 10.8°
B) 49.2°
C) 24.6°XXX
D) 13.5°
E) 17.7°
26)
FIGURE 6-11
27) Refer to Figure 6-11. Block A has a mass of 3.00 kg and rests on a smooth table and is connected to
block B, which has a mass of 2.00 kg, after passing over an ideal pulley, as shown. Block B is
released from rest. How long does it take block B to travel 80.0 cm?
A) 0.404 s
B) 0.935 s
C) 0.785 s
D) 0.494 s
E) 0.639 sXXX
27)
FIGURE 6-10
28) A 10-kg sign is held by two ropes as shown in Figure 6-10. What is the tension on rope A?
A) 72 N
B) 88 NXXX
C) 98 N
D) 69 N
E) 44 N
28)
29) A mass of 40.0 grams is attached to a vertical spring with a spring constant k = 20.0 N/m and
lowered slowly until the spring stops stretching. How much does the spring stretch?
A) 0.800 m
B) 0.200 m
C) 0.00200 m
D) 0.0816 m
E) 0.0196 mXXX
29)
5
30) A 50.0-kg box is resting on a horizontal floor. A force of 250 N directed at an angle of 26.0° below
the horizontal is applied to the box. What is the minimum coefficient of static friction between the
box and the surface required for the box to remain stationary?
A) 0.375XXX
B) 0.406
C) 0.654
D) 0.441
E) 0.866
30)
31) What type of acceleration does an object moving with constant speed in a circular path experience?
A) terminal acceleration.
B) constant acceleration.
C) linear acceleration.
D) free fall.
E) centripetal acceleration.XXX
31)
32) A 50.0-kg crate is being pulled along a horizontal, smooth surface. The pulling force is 10.0 N and
is directed 20.0° above the horizontal. What is the acceleration of the crate?
A) 0.0684 m/s 2
B) 0.200 m/s2
C) 0.0728 m/s 2
D) 0.188 m/s2 XXX
E) 0.376 m/s2
32)
33) A 400-kg box is lifted vertically upward with constant velocity by means of two cables pulling at
40.0° on either side of the vertical direction. What is the tension in each cable?
A) 231 N
B) 3920 N
C) 2560 NXXX
D) 400 N
E) 800 N
33)
34) A 4.00-kg block slides down a frictionless inclined plane with an acceleration 3.00 m/s2 . What is
the angle of the incline above horizontal?
A) 45.2°
B) 53.7°
C) 23.6°
D) 17.8°
E) 35.3°
34)
35) An object is being acted upon by three forces and moves with a constant velocity. One force is 60.0
N along the x-axis, the second is 75.0 N along a direction making a counterclockwise angle of
150.0° with the x-axis. What is the magnitude of the third force?
A) 130 N
B) 37.8 N
C) 135 N
D) 62.4 N
E) 67.5 N
35)
36) A 40.0-kg crate is being lowered by means of a rope. Its downward acceleration is 2.00 m/s 2. What
is the force exerted by the rope on the crate?
A) 312 NXXX
B) 472 N
C) 80.0 N
D) 40.0 N
E) 232 N
36)
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37) The following four forces act on a 4.00 kg object:
F1 = 300 N east
F2 = 700 N north
F3 = 500 N west
F4 = 600 N south
37)
38) An object of weight W is in free-fall close to the surface of Earth. What is the force that the object
exerts on Earth?
A) a force equal to WXXX
B) no force at all
C) a force less than W
D) a force greater than W
E) cannot be determined without additional information
38)
39) Can work be done on a system if there is no motion?
A) No, since a system which is not moving has no energy.
B) Yes, since motion is only relative.
C) No, since work involves a non-zero displacement.XXX
D) Yes, if the sum of the external forces is zero.
E) Yes, if an external force is acting on the system.
39)
40) Work done by STATIC FRICTION is always
A) parallel to the surface.
B) perpendicular to the surface.
C) positive.
D) zero.XXX
E) negative.
40)
41) An object hits a wall and bounces back with half of its original speed. What is the ratio of the final
kinetic energy to the initial kinetic energy?
A) 4
B) 1/2
C) 8
D) 1/4XXX
E) 2
41)
42) In the SI system of units, power has the same units as
A) Nm/s.XXX
B) W/s.
C) Jm/s.
42)
What is the acceleration of the object?
A) 300 N in a direction 63.4° north of west
B) 2100 N in a direction 26.6° north of west
C) 224 N in a direction 26.6° north of westXXX
D) 300 N in a direction 26.6° north of west
E) 224 N in a direction 63.4° north of west
D) Js/m.
E) W/m.
43) Consider a plot of the displacement (x) vs. applied force (F) for an ideal elastic spring. The slope of
the curve would be
A) the reciprocal of the acceleration of gravity.
B) the reciprocal of the spring constant.XXX
C) the reciprocal of the displacement.
D) the spring constant.
E) the acceleration of gravity.
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43)
44) A constant force of 20 N is applied to an object of mass 8.0 kg at an angle of 25° with the
horizontal. What is the work done by this force on the object if it causes a displacement of 2.0 m
along the horizontal direction?
A) 0 J
B) 17 J
C) 19 J
D) 40 J
E) 36 JXXX
44)
45) A 20.0-N weight slides down a rough inclined plane which makes an angle of 30.0° with the
horizontal. The weight starts from rest and gains a speed of 15.0 m/s after sliding 150 m. How
much work is done against friction? Use g = 10 m/s 2 .
A) 1270 JXXX
B) 229 J
C) 1500 J
D) -229 J
E) -1500 J
45)
FIGURE 7-5
46) An object is under the influence of a force as represented by the force vs. position graph in Figure
7-5. What is the work done as the object moves from 4 m to 6 m?
A) 20 JXXX
B) 0 J
C) 30 J
D) 70 J
E) 40 J
46)
FIGURE 7-4
A constant force of 100 N is applied to a mass of 40.0 kg as shown in Figure 7-4. The force causes a displacement of 20.0
m to this mass along the + x-axis. Neglect friction.
47) What is the work done by the component of the force in Figure 7-4 along the +x-axis?
A) 1520 JXXX
B) 2000 J
C) 1530 J
D) 2000 J
E) 1680 J
47)
48) An object of mass 10.0 kg is initially at rest. A 100 N force causes it to move horizontally through a
distance of 6.00 m. What is the change in the kinetic energy of this object?
A) 200 J
B) 0 J
C) 60.0 J
D) 600 JXXX
E) 1000 J
48)
49) What is the power needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to
40.0 m/s in 4.00 seconds?
A) 140 kW
B) 14.0 kW
C) 275 kWXXX
D) 100 kW
E) 10.0 kW
49)
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50) A spring with a spring constant of 2500 N/m. is stretched 4.00 cm. What is the work required to
stretch the spring?
A) 0 J
B) 4.00 J
C) 2.00 JXXX
D) 3.00 J
E) 1.00 J
50)
FIGURE 7-2
Three applied forces, F1 = 20.0 N, F2 = 40.0 N, and F3 = 10.0 N act on an object with a mass of 2.00 kg which can move
along an inclined plane as shown in the figure. The questions refer to the instant when the object has moved 0.600 m
along the surface of the inclined plane in the upward direction. Neglect friction and use g = 10.0 m/s2 .
51) Refer to Figure 7-2. What is the amount of work done by force F1 as the object moves up the
inclined plane?
A) 10.0 J
B) 11.0 J
C) 16.0 J
D) 0 J
E) 12.0 JXXX
51)
FIGURE 8-1
52) You need to load a crate of mass m onto the bed of a truck. One possibility is to lift the crate
straight up over a height h, equal to height of the truck's bed. The work done in this case is W1 .
The other possibility is to slide the crate up the frictionless ramp of length L as shown in Figure
8-1. In this case you perform work W2 . What statement is true?
A) W1 < W2
B) W1 > W2
C) W1 = W2 XXX
D) No simple relationship exists between W1 and W2.
52)
53) An acorn falls from a tree. Compare its kinetic energy K, to its potential energy U.
A) K decreases and U increases.
B) K decreases and U decreases.
C) K increases and U decreases.XXX
D) K increases and U increases.
E) Cannot be determined without knowing the initial height of the acorn.
53)
9
FIGURE 8-4
An object of mass 2 kg is held at the top of a triangular wedge as shown in Figure 8-4, and then released. The reference
level for potential energy is at the base of the triangle. Neglect friction and use g = 10 m/s2 .
54) Refer to Figure 8-4. What is the gravitational potential energy of the object at the top of the wedge?
A) 30 J
B) 40 J
C) 60 JXXX
D) 80 J
E) 100 J
54)
FIGURE 8-5
A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10
m/s2 .
55) Refer to Figure 8-5. What is the kinetic energy of the bead at point A?
A) 0 JXXX
B) 2.0 x 10 -2 J
C) 16 x 10 -3 J
D) 0.40 J
E) There is not enough information to solve this problem.
10
55)
FIGURE 8-6
A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical
height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s2 .
56) What is the total energy of the roller coaster at point B?
A) 20.2 × 10 3 J
B) 16.4 × 10 4 J
C) 16.4 × 10 3 J
D) 17.6 × 10 4 JXXX
E) There is not enough information to solve this problem.
56)
57) A force of 4.0 N applied to a spring compresses it by 8.0 cm. What is the amount of work done to
compress the spring by an additional amount of 5.0 cm?
A) 2.0 J
B) 50 N/m
C) 0.26 JXXX
D) 20 J
E) 0.50 J
57)
58) An 8 kg object moving with an initial velocity of 4 m/s comes to rest due to friction after it travels a
horizontal distance of 10 m. If the initial speed of the object is doubled, what distance will it travel
before coming to rest? Use g = 10 m/s2 .
A) 80 m
B) 10 m
C) 30 m
D) 20 m
E) 40 mXXX
58)
FIGURE 8-9
An object with a mass of 10.0 kg is at rest at the top of a frictionless inclined plane of height 8.00 m and an angle of
inclination 30.0° with the horizontal. The object is released from this position and it stops at a distance d from the bottom
of the inclined plane along a horizontal surface, as shown in Figure 8-9. The coefficient of kinetic friction for the
horizontal surface is 0.400 and g = 10.0 m/s2.
59) Refer to Figure 8-9. What is the speed of the object at the bottom of the inclined plane?
A) 8.00 m/s
B) 0 m/s
C) 10.0 m/s
D) 6.33 m/s
E) 12.6 m/sXXX
11
59)
FIGURE 8-7
Two masses M1 = 2.0 kg and M2 = 4.0 kg are attached by a string as shown in Figure 8-7. M1 falls vertically down and
M2 moves on a frictionless surface. Initially the system is at rest. Use g = 10 m/s2 .
60) Refer to Figure 8-7. What is the potential energy of the mass M1 just before it touches the ground?
A) 2.3 J
B) 2.5 J
C) 5.2 J
D) 4 J
E) 0 JXXX
60)
61) An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a
speed of 28 m/s. If the coefficient of friction between the object and the surface is 0.40, how far will
the object go before it comes to a stop? Use g = 10 m/s2 .
A) 61 cm
B) 23 m
C) 61 m
D) 98 mXXX
E) 98 cm
61)
FIGURE 8-11
A 2.0 kg mass is moving along the x-axis. The potential energy curve as a function of position is shown in Figure 8-11.
The system is conservative. There is no friction.
62) Refer to Figure 8-11. If the speed of the object at the origin is 4.0 m/s, what will be its speed at 7.0
m along the +x-axis?
A) 4.6 m/s
B) 4.0 m/s
C) 4.1 m/sXXX
D) 4.4 m/s
E) 10 m/s
12
62)
63) A golf club exerts an average force of 1000 N on a 0.045-kg golf ball which is initially at rest. The
club is in contact with the ball for 1.8 ms. What is the speed of the golf ball as it leaves the tee?
A) 50 m/s
B) 35 m/s
C) 30 m/s
D) 45 m/s
E) 40 m/sXXX
63)
64) A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s. The
cars stick together. What is the speed of the wreckage just after the collision?
A) 12.2 m/sXXX
B) 35.0 m/s
C) 25.0 m/s
D) 6.10 m/s
E) 17.3 m/s
64)
65) A 0.330-kg volleyball is thrown vertically downward with a speed of 0.150 m/s. It takes it 0.0655 s
to reach the ground. What is the magnitude of its momentum just before it hits the ground?
A) 0.262 kg·m/sXXX
B) 0.0418 kg·m/s
C) 0.163 kg·m/s
D) 0.0216 kg·m/s
E) 0.212 kg·m/s
65)
66) A 120-g rubber ball is thrown with a speed of 10 m/s at an oncoming 900-kg car which is
approaching at 30 m/s, and undergoes a one-dimensional elastic collision with the car. What is the
speed of the ball after the collision?
A) 50 m/s
B) 30 m/s
C) 10 m/s
D) 70 m/sXXX
E) 40 m/s
66)
67) A 320-g air track cart traveling at 1.25 m/s collides elastically with a stationary 270-g cart. What is
the speed of the 270-g cart after the collision?
A) 0.678 m/s
B) 2.72 m/s
C) 0.106 m/s
D) 1.36 m/sXXX
E) 1.14 m/s
67)
68) Three masses are located in the x-y plane as follows: a mass of 6 kg is located at (0 m, 0 m), a mass
of 4 kg is located at (3 m, 0 m), and a mass of 2 kg is located at (0 m, 3 m). Where is the center of
mass of the system?
A) (1 m, 1 m)
B) (0.5 m, 1 m)
C) (1 m, 0.5 m)XXX
D) (2 m, 1 m)
E) (1 m, 2 m)
68)
13
69) A 2.00-g bullet hits and becomes embedded in a 5.00-kg wood block which is hanging from a
1.20-m long string. This causes the block to swing through an arc of 3.50°. What was the speed of
the bullet before it hit the block?
A) 16.7 m/s
B) 789 m/s
C) 25.3 m/s
D) 262 m/s
E) 524 m/sXXX
69)
70) A 3.0-kg object moves to the right at 4.0 m/s. It collides head-on with a 6.0-kg object moving to
the left at 2.0 m/s. Which statement is correct?
A) The total momentum before the collision is 0 kg · m/s, and after the collision is 24 kg · m/s.
B) The total momentum both before and after the collision is 24 kg · m/s.
C) The total momentum both before and after the collision is zero.XXX
D) The total momentum before the collision is 24 kg · m/s, and after the collision is 0 kg · m/s.
E) None of the above is true.
70)
FIGURE 8-3
A mass is attached to one end of a string. The other end of the string is attached to a rigid support. The mass is released at
A and swings in a vertical arc to points B, C, and D, as shown in Figure 8-3. Neglect air resistance and use g = 10 m/s2 .
71) Refer to Figure 8-3. At what point does the mass have the most potential energy?
A) AXXX
B) B
C) C
D) D
E) none of the given points
71)
72) An object that is initially at rest breaks up into two pieces of unequal masses when a
spring-loaded device is released. If you compare the kinetic energy of the larger mass to that of the
smaller mass immediately after they separate, which of the following statements is correct?
A) The kinetic energies of the two masses are equal.
B) The kinetic energy of the smaller mass is greater.XXX
C) The total kinetic energy is zero J.
D) The kinetic energy of the larger mass is greater.
72)
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73) A rope is lying on a table. You pick up one end and start raising it with a constant velocity. The
force you have to exert on the rope is
A) greater than the weight of the portion of the rope that is not on the table.XXX
B) zero N.
C) less than the weight of the portion of the rope that is not on the table but not zero N.
D) equal to the weight of the portion of the rope that is not on the table.
E) Cannot be determined without additional information.
73)
74) An elastic collision of two objects is characterized by the following.
A) Total kinetic energy of the system remains constant.
B) Total momentum of the system is conserved.
C) Both A and B are true.XXX
D) Neither A nor B are true.
74)
15