Question 1

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

Accepted Answer

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)  perfectly elastic. 
B)  partially inelastic. 
C)  completely inelastic. 
D)  characterized by an increase in kinetic energy. 
E)  not possible because momentum is not conserved.

Question 2

A stone with a mass of 1.0 kg is tied to the end of a light string which keeps it moving in a circle with a constant speed of 4.0 m/s on a perfectly smooth horizontal tabletop. The radius of the path is 0.60 m. How much work does the tension in the string do on the stone as it makes one-half of a complete circle?

Accepted Answer

A)  100 J 
B)  3.8 J 
C)  0 J 
D)  40 J 
E)  80 J 
A)  100 J 
B)  3.8 J 
C)  0 J 
D)  40 J 
E)  80 J

Question 3

A stone initially moving at 8.0 m/s on a level surface comes to rest due to friction after it travels 11 m. What is the coefficient of kinetic friction between the stone and the surface?

Accepted Answer

A)  0.13 
B)  0.25 
C)  0.30 
D)  0.43 
E)  0.80 
A)  0.13 
B)  0.25 
C)  0.30 
D)  0.43 
E)  0.80

Question 4

A 0.46-kg block is held in place against the spring by a 30-N horizontal external force. The external force is removed, and the block is projected with a velocity $v_{1} = 1.2 \mathrm {~m} / \mathrm { s }$ upon separation from the spring, as shown in the figure. The block descends a ramp and has a velocity $v_{2} = 1.5 \mathrm {~m} / \mathrm { s }$ at the bottom. The track is frictionless between points A and B. The block enters a rough section at point B, extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.38. The velocity of the block is $v_{3} = 1.4 \mathrm {~m} / \mathrm { s }$ at point C. The block moves on to D, where it stops. What distance does the block travel between points B and D?

Accepted Answer

A)  0.30 m 
B)  0.039 m 
C)  0.26 m 
D)  0.40 m 
E)  0.60 m 
A)  0.30 m 
B)  0.039 m 
C)  0.26 m 
D)  0.40 m 
E)  0.60 m

Question 5

If electricity costs 7.06¢/kW∙h, how much would it cost you to run a $120 - W$ stereo system $\text { 4.0 hours }$ per day for $4.0 \text { weeks? }$

Accepted Answer

A)  $0.95 
B)  $0.14 
C)  $1.62 
D)  $2.66 
A)  $0.95 
B)  $0.14 
C)  $1.62 
D)  $2.66

Question 6

A hoop is rolling without slipping along a horizontal surface with a forward speed of 5.50 m/s when it starts up a ramp that makes an angle of 25.0° with the horizontal. What is the speed of the hoop after it has rolled 3.00 m up as measured along the surface of the ramp?

Accepted Answer

A)  4.22 m/s 
B)  1.91 m/s 
C)  2.06 m/s 
D)  3.79 m/s 
E)  8.02 m/s 
A)  4.22 m/s 
B)  1.91 m/s 
C)  2.06 m/s 
D)  3.79 m/s 
E)  8.02 m/s

Question 7

A prankster drops a water balloon from the top of a building. If the balloon is traveling at 29.1 m/s when it strikes a window ledge that is 1.5 m above the ground, how tall is the building? Neglect air resistance.

Accepted Answer

A)  45 m 
B)  43 m 
C)  46 m 
D)  47 m 
A)  45 m 
B)  43 m 
C)  46 m 
D)  47 m

Question 8

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 of the object?

Accepted Answer

A)  1/2 
B)  1/4 
C)  1/8 
D)  1/16 
A)  1/2 
B)  1/4 
C)  1/8 
D)  1/16

Question 9

An ideal spring stretches by 21.0 cm when a 135-N object is hung from it. If instead you hang a fish from this spring, what is the weight of a fish that would stretch the spring by $31.0 \mathrm {~cm} ?$

Accepted Answer

A)  199 N 
B)  91 N 
C)  145 N 
D)  279 N 
A)  199 N 
B)  91 N 
C)  145 N 
D)  279 N

Question 10

A roller coaster starting from rest descends 35 meters in its initial drop and then rises 23 meters when it goes over the first hill, which has a circular shape over the top. If a passenger at the top of the hill feels an apparent weight equal to one-half of her normal weight, what is the radius of curvature of the first hill? Neglect any frictional losses.

Accepted Answer

The answer of A roller coaster starting from rest descends...

Question 11

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

Accepted Answer

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. 
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.

Question 12

A child pulls on a wagon with a force of  75${~N}$ If the wagon moves a total of $42 \mathrm {~m}$ in $3.1 \mathrm {~min} \text {, }$ what is the average power delivered by the child?

Accepted Answer

A)  17 W 
B)  21 W 
C)  22 W 
D)  26 W 
A)  17 W 
B)  21 W 
C)  22 W 
D)  26 W

Question 13

The figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves point Q from rest, what is its speed at the top of the 25-m peak (point S)?

Accepted Answer

A)  10 m/s 
B)  22 m/s 
C)  44 m/s 
D)  62 m/s 
E)  120 m/s 
A)  10 m/s 
B)  22 m/s 
C)  44 m/s 
D)  62 m/s 
E)  120 m/s

Question 14

If 4.0 J of work are performed in stretching an ideal spring with a spring constant (force constant) of 2500 N/m, by what distance is the spring stretched?

Accepted Answer

A)  3.2 cm 
B)  3.2 m 
C)  0.3 cm 
D)  5.7 m 
E)  5.7 cm 
A)  3.2 cm 
B)  3.2 m 
C)  0.3 cm 
D)  5.7 m 
E)  5.7 cm

Question 15

The graphs shown show the magnitude F of the force exerted by a spring as a function of the distance x the spring has been stretched. For which one of the graphs does the spring obey Hooke's law? 
a)
 
b)
 
c)
 
d)
 
e)

Accepted Answer

A)  Graph a 
B)  Graph b 
C)  Graph c 
D)  Graph d 
E)  Graph e 
A)  Graph a 
B)  Graph b 
C)  Graph c 
D)  Graph d 
E)  Graph e

Question 16

A stone can slide down one of four different frictionless ramps, as shown in the figure. For which ramp will the speed of the ball be the greatest at the bottom?

Accepted Answer

A)  Ramp X 
B)  Ramp Y 
C)  Ramp Z 
D)  The speed of the ball will be the same for all ramps. 
A)  Ramp X 
B)  Ramp Y 
C)  Ramp Z 
D)  The speed of the ball will be the same for all ramps.

Question 17

A uniform ball with diameter of 10 cm rolls without slipping on a horizontal tabletop. The moment of inertia of the ball about an axis through its center is 2.2 × 10-3 kg ∙ m2, and the translational speed of its center is 0.45 m/s.
(a) What is its angular speed of the ball about its center of mass?
(b) What is the rotational kinetic energy of the ball?
(c) What is the ball's angular momentum about its center of mass?

Accepted Answer

(a) 9.0 ra

Question 18

A solid wooden door, 90 cm wide by 2.0 m tall, has a mass of 35 kg. It is open and at rest. A small 500-g ball is thrown perpendicular to the door with a speed of 20 m/s and hits the door 60 cm from the hinged side, causing it to begin turning. The ball rebounds along the same line with a speed of 16.0 m/s relative to the ground. How much energy is lost during this collision?

Accepted Answer

A)  30 J 
B)  16 J 
C)  15 J 
D)  13 J 
E)  4.8 J 
A)  30 J 
B)  16 J 
C)  15 J 
D)  13 J 
E)  4.8 J

Question 19

A 1500-kg car accelerates from rest to 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 hp = 746 W)

Accepted Answer

A)  60 hp 
B)  70 hp 
C)  80 hp 
D)  90 hp 
A)  60 hp 
B)  70 hp 
C)  80 hp 
D)  90 hp

Question 20

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?

Accepted Answer

A)  the heavier object 
B)  the lighter object 
C)  They both have the same kinetic energy. 
A)  the heavier object 
B)  the lighter object 
C)  They both have the same kinetic energy.

Exam 10: Energy and Work

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

A stone initially moving at 8.0 m/s on a level surface comes to rest due to friction after it travels 11 m. What is the coefficient of kinetic friction between the stone and the surface?

If electricity costs 7.06¢/kW∙h, how much would it cost you to run a 120−W120 - W120−W stereo system 4.0 hours \text { 4.0 hours } 4.0 hours per day for 4.0 weeks? 4.0 \text { weeks? }4.0 weeks?

A hoop is rolling without slipping along a horizontal surface with a forward speed of 5.50 m/s when it starts up a ramp that makes an angle of 25.0° with the horizontal. What is the speed of the hoop after it has rolled 3.00 m up as measured along the surface of the ramp?

A prankster drops a water balloon from the top of a building. If the balloon is traveling at 29.1 m/s when it strikes a window ledge that is 1.5 m above the ground, how tall is the building? Neglect air resistance.

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 of the object?

An ideal spring stretches by 21.0 cm when a 135-N object is hung from it. If instead you hang a fish from this spring, what is the weight of a fish that would stretch the spring by 31.0 cm?31.0 \mathrm {~cm} ?31.0 cm?

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 child pulls on a wagon with a force of 75 N{~N} N If the wagon moves a total of 42 m42 \mathrm {~m}42 m in 3.1 min, 3.1 \mathrm {~min} \text {, }3.1 min, what is the average power delivered by the child?

The figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves point Q from rest, what is its speed at the top of the 25-m peak (point S)?

If 4.0 J of work are performed in stretching an ideal spring with a spring constant (force constant) of 2500 N/m, by what distance is the spring stretched?

The graphs shown show the magnitude F of the force exerted by a spring as a function of the distance x the spring has been stretched. For which one of the graphs does the spring obey Hooke's law? a) b) c) d) e)

A stone can slide down one of four different frictionless ramps, as shown in the figure. For which ramp will the speed of the ball be the greatest at the bottom?

A 1500-kg car accelerates from rest to 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 hp = 746 W)

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?

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If electricity costs 7.06¢/kW∙h, how much would it cost you to run a $120 - W$ stereo system $\text { 4.0 hours }$ per day for $4.0 \text { weeks? }$

An ideal spring stretches by 21.0 cm when a 135-N object is hung from it. If instead you hang a fish from this spring, what is the weight of a fish that would stretch the spring by $31.0 \mathrm {~cm} ?$

A child pulls on a wagon with a force of 75 ${~N}$ If the wagon moves a total of $42 \mathrm {~m}$ in $3.1 \mathrm {~min} \text {, }$ what is the average power delivered by the child?