Question 1

At time t = 0 a 2-kg particle has a velocity of (4 m/s)   - (3 m/s)   .At t = 3 s its velocity is (2 m/s)   + (3 m/s)   .During this time the work done on it was:

Accepted Answer

A) 4 J 
B) -4 J 
C) -12 J 
D) -40 J 
E) (4 J)   + (36 J)
  
A) 4 J 
B) -4 J 
C) -12 J 
D) -40 J 
E) (4 J)   + (36 J)
  C

Question 2

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

Question 3

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

Question 4

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

Question 5

A 50-N force acts on a 2-kg crate that starts from rest.When the force has been acting for 2 s the rate at which it is doing work is:

Accepted Answer

A) 100 W 
B) 1000 W 
C) 2500 W 
D) 5000 W 
E) 63000 W 
A) 100 W 
B) 1000 W 
C) 2500 W 
D) 5000 W 
E) 63000 W

Question 6

A 100-kg piano rolls down a 20° incline.A man tries to keep it from accelerating, and manages to keep its acceleration to 1.2 m/s2.If the piano rolls 5 m, what is the net work done on it by all the forces acting on it?

Accepted Answer

A) 60 J 
B) 100 J 
C) 600 J 
D) 1000 J 
E) 4900 J 
A) 60 J 
B) 100 J 
C) 600 J 
D) 1000 J 
E) 4900 J

Question 7

A 2-kg object is moving at 3 m/s.A 4-N force is applied in the direction of motion and then removed after the object has traveled an additional 5 m.The work done by this force is:

Accepted Answer

A) 9 J 
B) 18 J 
C) 20 J 
D) 29 J 
E) 38 J 
A) 9 J 
B) 18 J 
C) 20 J 
D) 29 J 
E) 38 J

Question 8

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 
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 9

Which of the following five units represents a quantity that is NOT the same type as the other four?

Accepted Answer

A) joule 
B) erg 
C) watt 
D) foot.pound 
E) newton.meter 
A) joule 
B) erg 
C) watt 
D) foot.pound 
E) newton.meter

Question 10

A man moves the 10-g object shown in a vertical plane at a constant speed from position X to position Y along a circular track of radius 20 m.The process takes 0.75 min.The work done by the man is about:

Accepted Answer

A) 1 J 
B) 2 J 
C) 4 J 
D) 6 J 
E) 12 J 
A) 1 J 
B) 2 J 
C) 4 J 
D) 6 J 
E) 12 J

Question 11

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. 
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 12

An 8-N block slides down an incline.It has an initial speed of 7 m/s.The work done by the resultant force on this block is:

Accepted Answer

A) 20 J 
B) 28 J 
C) 56 J 
D) impossible to calculate without more information 
E) none of these 
A) 20 J 
B) 28 J 
C) 56 J 
D) impossible to calculate without more information 
E) none of these

Question 13

A crate moves 10 m to the right on a horizontal surface as a woman pulls on it with a 10-N force.Rank the situations shown below according to the work done by her force, least to greatest.

Accepted Answer

A) 1,2,3 
B) 2,1,3 
C) 2,3,1 
D) 1,3,2 
E) 3,2,1, 
A) 1,2,3 
B) 2,1,3 
C) 2,3,1 
D) 1,3,2 
E) 3,2,1,

Question 14

A man pulls a 100-N crate up a frictionless 30°slope 5 m high as shown.Assuming that the crate moves at constant speed, the work done by the man is:

Accepted Answer

A) -500 J 
B) -250 J 
C) 0 J 
D) 250 J 
E) 500 J 
A) -500 J 
B) -250 J 
C) 0 J 
D) 250 J 
E) 500 J

Question 15

An object is constrained by a cord to move in a circular path of radius 0.5m on a horizontal frictionless surface.The cord will break if its tension exceeds 16N.The maximum kinetic energy the object can have is:

Accepted Answer

A) 4 J 
B) 8 J 
C) 16 J 
D) 32 J 
E) 64 J 
A) 4 J 
B) 8 J 
C) 16 J 
D) 32 J 
E) 64 J

Question 16

A man pulls a sled along a rough horizontal surface by applying a constant force   at an angle $\theta$above the horizontal.In pulling the sled a horizontal distance d, the work done by the man is:

Accepted Answer

A) Fd 
B) Fd cos $\theta$ 
C) Fd sin $\theta$ 
D) Fd/cos $\theta$ 
E) Fd/sin $\theta$ 
A) Fd 
B) Fd cos $\theta$ 
C) Fd sin $\theta$ 
D) Fd/cos $\theta$ 
E) Fd/sin $\theta$

Question 17

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

Question 18

The work done by gravity during the descent of a projectile is:

Accepted Answer

A) positive 
B) negative 
C) zero 
D) depends for its sign on the direction of the y axis 
E) depends for its sign on the direction of both the x and y axes 
A) positive 
B) negative 
C) zero 
D) depends for its sign on the direction of the y axis 
E) depends for its sign on the direction of both the x and y axes

Question 19

A particle starts from rest and is acted on by a net force that does work at a rate that is proportional to the time t.The speed of the particle is proportional to:

Accepted Answer

A)    
B) t 
C) t2 
D) 1/   
E) 1/t 
A)    
B) t 
C) t2 
D) 1/   
E) 1/t

Question 20

A crate is initially at rest on a horizontal frictionless table.A constant horizontal force F is applied.Which of the following five graphs is a correct plot of work W as a function of crate speed v?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Exam 7: Kinetic Energy and Work

At time t = 0 a 2-kg particle has a velocity of (4 m/s) - (3 m/s) .At t = 3 s its velocity is (2 m/s) + (3 m/s) .During this time the work done on it was:

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:

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?

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:

A 50-N force acts on a 2-kg crate that starts from rest.When the force has been acting for 2 s the rate at which it is doing work is:

A 100-kg piano rolls down a 20° incline.A man tries to keep it from accelerating, and manages to keep its acceleration to 1.2 m/s2.If the piano rolls 5 m, what is the net work done on it by all the forces acting on it?

A 2-kg object is moving at 3 m/s.A 4-N force is applied in the direction of motion and then removed after the object has traveled an additional 5 m.The work done by this force is:

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?

Which of the following five units represents a quantity that is NOT the same type as the other four?

A man moves the 10-g object shown in a vertical plane at a constant speed from position X to position Y along a circular track of radius 20 m.The process takes 0.75 min.The work done by the man is about:

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

An 8-N block slides down an incline.It has an initial speed of 7 m/s.The work done by the resultant force on this block is:

A crate moves 10 m to the right on a horizontal surface as a woman pulls on it with a 10-N force.Rank the situations shown below according to the work done by her force, least to greatest.

A man pulls a 100-N crate up a frictionless 30°slope 5 m high as shown.Assuming that the crate moves at constant speed, the work done by the man is:

An object is constrained by a cord to move in a circular path of radius 0.5m on a horizontal frictionless surface.The cord will break if its tension exceeds 16N.The maximum kinetic energy the object can have is:

A man pulls a sled along a rough horizontal surface by applying a constant force at an angle θ\thetaθ above the horizontal.In pulling the sled a horizontal distance d, the work done by the man is:

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:

The work done by gravity during the descent of a projectile is:

A particle starts from rest and is acted on by a net force that does work at a rate that is proportional to the time t.The speed of the particle is proportional to:

A crate is initially at rest on a horizontal frictionless table.A constant horizontal force F is applied.Which of the following five graphs is a correct plot of work W as a function of crate speed v?

Measurement

Motion Along a Straight Line

Vectors

Motion in Two and Three Dimensions

Force and Motion

Force and Motion

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

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Oscillations

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Waves

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The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Coulombs Law

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Gauss Law

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Magnetic Fields Due to Currents

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Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

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Interference 1

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

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Conduction of Electricity in Solids

Energy From the Nucleus

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Filters

A 100-kg piano rolls down a 20° incline.A man tries to keep it from accelerating, and manages to keep its acceleration to 1.2 m/s².If the piano rolls 5 m, what is the net work done on it by all the forces acting on it?