Question 1

A 1.5 kg crate falls from a height of 2.0 m onto an industrial spring scale with a spring constant of 1.5*105 N/m.At its greatest compression the reading on the scale is:

Accepted Answer

A)  15 N
B)  29 N
C)  1.5 * 103 N
D)  2.1 * 103 N
E)  3.0 * 103 N

Question 2

A watt .second is a unit of:

Accepted Answer

A)  force
B)  power
C)  displacement
D)  speed
E)  energy

Question 3

In raising an object to a given height by means of an inclined plane, as compared with raising the object vertically, there is a reduction in:

Accepted Answer

A)  work required
B)  distance pushed
C)  friction
D)  force required
E)  value of the acceleration due to gravity

Question 4

A mass of 47 kg is moving horizontally as a force of 190 N, directed at 25° below the horizontal, is exerted on it.When its speed is 7.3 m/s, what is the rate at which the force is doing work?

Accepted Answer

A)  0 W
B)  340 W
C)  590 W
D)  1300 W
E)  1400 W

Question 5

In the plot shown of force vs.distance, approximately how much work is done in moving an object from x = 5 m to x = 15 m?

Accepted Answer

A)  10 J
B)  55 J
C)  125 J
D)  275 J
E)  cannot be calculated without knowing the mass of the object

Question 6

A person holds an 80-N weight 2 m above the floor for 30 seconds.The power required to do this is:

Accepted Answer

A)  5.3 W
B)  40 W
C)  80 W
D)  160 W
E)  none of these

Question 7

A 0.50-kg object moves in a horizontal circular track with a radius of 2.5 m.An external force of 3.0 N, always tangent to the track, causes the object to speed up as it goes around.If it starts from rest its speed at the end of one revolution is:

Accepted Answer

A)  5.5 m/s
B)  14 m/s
C)  15 m/s
D)  18 m/s
E)  21 m/s

Question 8

A 1-kg block is lifted vertically 1 m at constant speed by a boy.The work done by the boy is about:

Accepted Answer

A)  1 ft .0lb
B)  1 J
C)  10 J
D)  0.1 J
E)  0 J

Question 9

This plot shows an object being moved by a series of forces.Which segments of the motion could have been caused by fixed springs?

Accepted Answer

A)  None of the segments could represent work being done by springs.
B)  Any of the segments could represent work being done by springs.
C)  Segments A and C only.
D)  Segments B and D only.
E)  Segment A only.

Question 10

An ideal spring, with a pointer attached to its end, hangs next to a scale.With a 100-N weight attached, the pointer indicates "40" on the scale as shown.Using a 200-N weight instead results in "60" on the scale.Using an unknown weight X instead results in "30" on the scale.The weight of X is:

Accepted Answer

A)  20 N
B)  30 N
C)  40 N
D)  50 N
E)  75 N

Question 11

The weight of an object on the moon is one-sixth of its weight on the Earth.The ratio of the kinetic energy of a body on the Earth moving with speed V to that of the same body moving with speed V on the moon is:

Accepted Answer

A)  6:1
B)  36:1
C)  1:1
D)  1:6
E)  1:36

Question 12

Which of the following is NOT a correct unit for work?

Accepted Answer

A)  erg
B)  ft.lb
C)  watt
D)  newton.meter
E)  joule

Question 13

Two objects with masses, m1 and m2, have the same kinetic energy and are both moving to the right.The same constant force is applied to the left to both masses.If m1 = 4m2, the ratio of the stopping distance of m1 to that of m2 is:

Accepted Answer

A)  1:4
B)  4:1
C)  1:2
D)  2:1
E)  1:1

Question 14

An 8000-N car is traveling at 12 m/s along a horizontal road when the brakes are applied.The car skids to a stop in 4.0 s.How much kinetic energy does the car lose in this time?

Accepted Answer

A)  4.8 * 104 J
B)  5.9 * 104 J
C)  1.2 * 105 J
D)  5.8 * 105 J
E)  4.8 * 106 J

Question 15

The velocity of a particle moving along the x axis changes from vi to vf.For which values of vi and vf is the total work done on the particle positive?

Accepted Answer

A)  vi = 5m/s, vf = 2m/s
B)  vi = 5m/s, vf = -2m/s
C)  vi = -5m/s, vf = -2m/s
D)  vi = -5m/s, vf = 2m/s
E)  vi = -2m/s, vf = -5m/s

Question 16

A 50-N force is the only force on a 2-kg crate that starts from rest.At the instant the crate has gone 2 m the rate at which the force is doing work is:

Accepted Answer

A)  2.5 W
B)  25 W
C)  75 W
D)  100 W
E)  500 W

Question 17

A 5.0-kg cart is moving horizontally at 6.0 m/s.In order to change its speed to 10.0 m/s, the net work done on the cart must be:

Accepted Answer

A)  20 J
B)  40 J
C)  90 J
D)  160 J
E)  400 J

Question 18

A sledge (including load) weighs 5000 N.It is pulled on level snow by a dog team exerting a horizontal force on it.The coefficient of kinetic friction between sledge and snow is 0.05.How much work is done by the dog team pulling the sledge 1000 m at constant speed?

Accepted Answer

A)  0 J
B)  2.5 * 105 J
C)  5.0 * 105 J
D)  2.5 *106 J
E)  5.0 *106 J

Question 19

Which of the following groups does NOT contain a scalar quantity?

Accepted Answer

A)  velocity, force, energy
B)  displacement, acceleration, force
C)  acceleration, speed, energy
D)  energy, force, distance
E)  energy, weight, time

Question 20

Power has the dimensions of:

Accepted Answer

A)  ML2/T2
B)  MT/L2
C)  ML/T2
D)  ML2/T3
E)  none of these

Exam 7: Kinetic Energy and Work

In raising an object to a given height by means of an inclined plane, as compared with raising the object vertically, there is a reduction in:

Correct AnswerverifiedShow Answer

An 8000-N car is traveling at 12 m/s along a horizontal road when the brakes are applied.The car skids to a stop in 4.0 s.How much kinetic energy does the car lose in this time?

Correct AnswerverifiedShow Answer

A 5.0-kg cart is moving horizontally at 6.0 m/s.In order to change its speed to 10.0 m/s, the net work done on the cart must be:

Correct AnswerverifiedShow Answer

In the plot shown of force vs.distance, approximately how much work is done in moving an object from x = 5 m to x = 15 m?

Correct AnswerverifiedShow Answer

A 1.5 kg crate falls from a height of 2.0 m onto an industrial spring scale with a spring constant of 1.5*105 N/m.At its greatest compression the reading on the scale is:

Correct AnswerverifiedShow Answer

A sledge (including load) weighs 5000 N.It is pulled on level snow by a dog team exerting a horizontal force on it.The coefficient of kinetic friction between sledge and snow is 0.05.How much work is done by the dog team pulling the sledge 1000 m at constant speed?

Correct AnswerverifiedShow Answer

A watt .second is a unit of:

Correct AnswerverifiedShow Answer

A mass of 47 kg is moving horizontally as a force of 190 N, directed at 25° below the horizontal, is exerted on it.When its speed is 7.3 m/s, what is the rate at which the force is doing work?

Correct AnswerverifiedShow Answer

An ideal spring, with a pointer attached to its end, hangs next to a scale.With a 100-N weight attached, the pointer indicates "40" on the scale as shown.Using a 200-N weight instead results in "60" on the scale.Using an unknown weight X instead results in "30" on the scale.The weight of X is:

Correct AnswerverifiedShow Answer

A person holds an 80-N weight 2 m above the floor for 30 seconds.The power required to do this is:

Correct AnswerverifiedShow Answer

A 0.50-kg object moves in a horizontal circular track with a radius of 2.5 m.An external force of 3.0 N, always tangent to the track, causes the object to speed up as it goes around.If it starts from rest its speed at the end of one revolution is:

Correct AnswerverifiedShow Answer

A 1-kg block is lifted vertically 1 m at constant speed by a boy.The work done by the boy is about:

Correct AnswerverifiedShow Answer

A 50-N force is the only force on a 2-kg crate that starts from rest.At the instant the crate has gone 2 m the rate at which the force is doing work is:

Correct AnswerverifiedShow Answer

The weight of an object on the moon is one-sixth of its weight on the Earth.The ratio of the kinetic energy of a body on the Earth moving with speed V to that of the same body moving with speed V on the moon is:

Correct AnswerverifiedShow Answer

Which of the following groups does NOT contain a scalar quantity?

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Power has the dimensions of:

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The velocity of a particle moving along the x axis changes from vi to vf.For which values of vi and vf is the total work done on the particle positive?

Correct AnswerverifiedShow Answer

This plot shows an object being moved by a series of forces.Which segments of the motion could have been caused by fixed springs?

Correct AnswerverifiedShow Answer

Which of the following is NOT a correct unit for work?

Correct AnswerverifiedShow Answer

Two objects with masses, m1 and m2, have the same kinetic energy and are both moving to the right.The same constant force is applied to the left to both masses.If m1 = 4m2, the ratio of the stopping distance of m1 to that of m2 is:

Correct AnswerverifiedShow Answer

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A 1.5 kg crate falls from a height of 2.0 m onto an industrial spring scale with a spring constant of 1.5*10⁵ N/m.At its greatest compression the reading on the scale is:

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The velocity of a particle moving along the x axis changes from v_i to v_f.For which values of v_i and v_f is the total work done on the particle positive?

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Two objects with masses, m₁ and m₂, have the same kinetic energy and are both moving to the right.The same constant force is applied to the left to both masses.If m₁ = 4m₂, the ratio of the stopping distance of m₁ to that of m₂ is:

Correct Answer
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