Question 1

Which of the following is the correct combination of dimensions for energy?

Accepted Answer

A)  MLT 
B)  LT2 /M 
C)  ML2/T2 
D)  M2L3T 
E)  ML/T2 
A)  MLT 
B)  LT2 /M 
C)  ML2/T2 
D)  M2L3T 
E)  ML/T2

Question 2

Two trailers, X with mass 500 kg and Y with mass 2000 kg, are being pulled at the same speed. The ratio of the kinetic energy of Y to that of X is:

Accepted Answer

A)  1:1 
B)  2:1 
C)  4:1 
D)  9:1 
E)  1500:1 
A)  1:1 
B)  2:1 
C)  4:1 
D)  9:1 
E)  1500:1

Question 3

A watt.second is a unit of:

Accepted Answer

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

Question 4

A man pushes an 80-N crate a distance of 5.0 m upward along a frictionless slope that makes an angle of 30 $\degree$with the horizontal. The force he exerts is parallel to the slope. If the speed of the crate is constant, then the work done by the man is:

Accepted Answer

A)  -200 J 
B)  61 J 
C)  140 J 
D)  200 J 
E)  260 J 
A)  -200 J 
B)  61 J 
C)  140 J 
D)  200 J 
E)  260 J

Question 5

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. The work done by the external force as the mass makes one revolution is:

Accepted Answer

A)  7.5 J 
B)  24 J 
C)  47 J 
D)  94 J 
E)  120 J 
A)  7.5 J 
B)  24 J 
C)  47 J 
D)  94 J 
E)  120 J

Question 6

The mechanical advantage of any machine is:

Accepted Answer

A)  the efficiency of the machine 
B)  the work done by the machine 
C)  the ratio of the work done by the machine to the work expended on it 
D)  the ratio of the force exerted by the machine to the force applied to it 
E)  the ratio of the force applied to the machine to the force exerted by it 
A)  the efficiency of the machine 
B)  the work done by the machine 
C)  the ratio of the work done by the machine to the work expended on it 
D)  the ratio of the force exerted by the machine to the force applied to it 
E)  the ratio of the force applied to the machine to the force exerted by it

Question 7

A particle moves 5 m in the positive x direction while being acted upon by a constant force = (4 N) + (2 N) - (4 N). The work done on the particle by this force is:

Accepted Answer

A)  20 J 
B)  10 J 
C)  -20 J 
D)  30 J 
E)  is impossible to calculate without knowing other forces 
A)  20 J 
B)  10 J 
C)  -20 J 
D)  30 J 
E)  is impossible to calculate without knowing other forces

Question 8

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 9

A spring of spring constant k is attached to a block of mass m. The spring moves the block through a displacement x. How can you calculate how much work the spring does on the block?

Accepted Answer

A)  Multiply the spring force, kx, by the distance x. 
B)  Multiply the spring force, ½ kx2, by the distance x. 
C)  Integrate the spring force, kx, over the distance x. 
D)  Integrate the spring force, ½ kx2, over the time it takes the block to move. 
E)  You cannot calculate this without knowing the acceleration of the block. 
A)  Multiply the spring force, kx, by the distance x. 
B)  Multiply the spring force, ½ kx2, by the distance x. 
C)  Integrate the spring force, kx, over the distance x. 
D)  Integrate the spring force, ½ kx2, over the time it takes the block to move. 
E)  You cannot calculate this without knowing the acceleration of the block.

Question 10

A particle moving along the x axis is acted upon by a single force F = F0e-kx, where F0 and k are constants. The particle is released from rest at x = 0. It will attain a maximum kinetic energy of:

Accepted Answer

A)  F0/k 
B)  F0/ek 
C)  kF0 
D)  1/2(kF0)2 
E)  kekF0 
A)  F0/k 
B)  F0/ek 
C)  kF0 
D)  1/2(kF0)2 
E)  kekF0

Question 11

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 12

An ideal spring is hung vertically from the ceiling. When a 2.0-kg mass hangs at rest from it, the spring is extended 6.0 cm from its relaxed length. An upward external force is then applied to the block to move it upward a distance of 16 cm. While the block is being raised by the force, the work done by the spring is

Accepted Answer

A)  -1.0 J 
B)  -0.52 J 
C)  -0.26 J 
D)  0.52 J 
E)  1.0 J 
A)  -1.0 J 
B)  -0.52 J 
C)  -0.26 J 
D)  0.52 J 
E)  1.0 J

Question 13

A 0.50-kg object moves on a horizontal frictionless 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, then at the end of one revolution the radial component of the force of the track on it is:

Accepted Answer

A)  19 N 
B)  38 N 
C)  47 N 
D)  75 N 
E)  96 N 
A)  19 N 
B)  38 N 
C)  47 N 
D)  75 N 
E)  96 N

Question 14

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

Question 15

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

Question 16

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 17

A Boston Red Sox baseball player catches a ball of mass m that is moving toward him with speed v. While bringing the ball to rest, his hand moves back a distance d. Assuming constant deceleration, the horizontal force exerted on the ball by his hand is:

Accepted Answer

A)  mv/d 
B)  mvd 
C)  mv2/d 
D)  2mv/d 
E)  mv2/(2d) 
A)  mv/d 
B)  mvd 
C)  mv2/d 
D)  2mv/d 
E)  mv2/(2d)

Question 18

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 19

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

Question 20

A boy holds a 40-N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is:

Accepted Answer

A)  0 J 
B)  6.1 J 
C)  40 J 
D)  60 J 
E)  90 J 
A)  0 J 
B)  6.1 J 
C)  40 J 
D)  60 J 
E)  90 J

Exam 7: Kinetic Energy and Work

Which of the following is the correct combination of dimensions for energy?

Two trailers, X with mass 500 kg and Y with mass 2000 kg, are being pulled at the same speed. The ratio of the kinetic energy of Y to that of X is:

A watt.second is a unit of:

A man pushes an 80-N crate a distance of 5.0 m upward along a frictionless slope that makes an angle of 30 °\degree° with the horizontal. The force he exerts is parallel to the slope. If the speed of the crate is constant, then the work done by the man is:

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. The work done by the external force as the mass makes one revolution is:

The mechanical advantage of any machine is:

A particle moves 5 m in the positive x direction while being acted upon by a constant force = (4 N) + (2 N) - (4 N). The work done on the particle by this force 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 spring of spring constant k is attached to a block of mass m. The spring moves the block through a displacement x. How can you calculate how much work the spring does on the block?

A particle moving along the x axis is acted upon by a single force F = F0e-kx, where F0 and k are constants. The particle is released from rest at x = 0. It will attain a maximum kinetic energy of:

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?

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:

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:

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 Boston Red Sox baseball player catches a ball of mass m that is moving toward him with speed v. While bringing the ball to rest, his hand moves back a distance d. Assuming constant deceleration, the horizontal force exerted on the ball by his hand is:

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:

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 boy holds a 40-N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

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Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

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A man pushes an 80-N crate a distance of 5.0 m upward along a frictionless slope that makes an angle of 30 $\degree$ with the horizontal. The force he exerts is parallel to the slope. If the speed of the crate is constant, then the work done by the man is:

A particle moving along the x axis is acted upon by a single force F = F₀e^-kx, where F₀ and k are constants. The particle is released from rest at x = 0. It will attain a maximum kinetic energy of:

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 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: