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

A kilowatt hour is a unit of:

Accepted Answer

A) power 
B) energy/time 
C) energy 
D) power/time 
E) force/distance 
A) power 
B) energy/time 
C) energy 
D) power/time 
E) force/distance

Question 3

The amount of work required to stop a moving object is equal to the:

Accepted Answer

A) velocity of the object 
B) kinetic energy of the object 
C) mass of the object times its acceleration 
D) mass of the object times its velocity 
E) square of the velocity of the object 
A) velocity of the object 
B) kinetic energy of the object 
C) mass of the object times its acceleration 
D) mass of the object times its velocity 
E) square of the velocity of the object

Question 4

An object moves in a circle at constant speed.The work done by the centripetal force is zero because:

Accepted Answer

A) the displacement for each revolution is zero 
B) the average force for each revolution is zero 
C) there is no friction 
D) the magnitude of the acceleration is zero 
E) the centripetal force is perpendicular to the velocity 
A) the displacement for each revolution is zero 
B) the average force for each revolution is zero 
C) there is no friction 
D) the magnitude of the acceleration is zero 
E) the centripetal force is perpendicular to the velocity

Question 5

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.A downward external force is now applied to the mass to extend the spring an additional 10 cm.While the spring is being extended by the force, the work done by the spring is:

Accepted Answer

A) -3.6 J 
B) -3.3 J 
C) -1.0 J 
D) 3.3 J 
E) 3.6 J 
A) -3.6 J 
B) -3.3 J 
C) -1.0 J 
D) 3.3 J 
E) 3.6 J

Question 6

A man pulls a 100-N crate up a frictionless 30$\degree$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 7

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 8

Camping equipment weighing 6000 N is pulled across a frozen lake by means of a horizontal rope.The coefficient of kinetic friction is 0.05.The work done by the campers in pulling the equipment 1000 m at constant velocity is:

Accepted Answer

A) 0 J 
B) 1.5 * 105 J 
C) 3.0 * 105 J 
D) 2.9 * 106 J 
E) 6.0 *106 J 
A) 0 J 
B) 1.5 * 105 J 
C) 3.0 * 105 J 
D) 2.9 * 106 J 
E) 6.0 *106 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

Which of the following bodies has the largest kinetic energy?

Accepted Answer

A) Mass 3M and speed V 
B) Mass 3M and speed 2V 
C) Mass 2M and speed 3V 
D) Mass M and speed 4V 
E) All four of the above have the same kinetic energy 
A) Mass 3M and speed V 
B) Mass 3M and speed 2V 
C) Mass 2M and speed 3V 
D) Mass M and speed 4V 
E) All four of the above have the same kinetic energy

Question 11

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

Question 12

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

Exam 7: Kinetic Energy and Work

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

A kilowatt hour is a unit of:

The amount of work required to stop a moving object is equal to the:

An object moves in a circle at constant speed.The work done by the centripetal force is zero because:

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

Camping equipment weighing 6000 N is pulled across a frozen lake by means of a horizontal rope.The coefficient of kinetic friction is 0.05.The work done by the campers in pulling the equipment 1000 m at constant velocity 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?

Which of the following bodies has the largest kinetic energy?

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

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

Waves I

Waves II

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

Filters

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: