Physics 121 General Physics
Concept Quizzes
Chapter 7. Energy and Energy Transfer
Chapter 8. Potential Energy

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Which statement about work is true?

A force can only do work if it points in the same direction as the displacement.
Only the component of a force parallel to the displacement does work.
The component of a force perpendicular to the displacement does positive work.
Only the net force on an object does any work.

A box is lifted vertically 1.5 m and is then held there. The box has weight 100 N. Ignore friction.

1. How much work is being done in holding the box in this elevated position?

150 J
More than 150 J.
Less than 150 J.
No work is being done.

2. How much work was done by the lifting force as the box was raised the 1.5 m?

150 J
More than 150 J.
Less than 150 J.
No work was done.

3. Now suppose that there is some friction with the air as the box is raised. How much work was done by the lifting force as the box was raised the 1.5 m?

150 J
More than 150 J.
Less than 150 J.
No work was done.

A sphere falls from rest through the atmosphere (friction is present) gaining 10 J of Kinetic Energy. How much gravitational potential energy did it lose?

10 J.
More than 10 J.
Less than 10 J.
It is impossible to tell.

A woman pulls a crate up a rough inclined plane at a constant speed. Which statement is not true?

The work done on the object by gravity is zero.
The gravitational PE of the crate is increasing.
The work done by the net force acting on the crate is zero.
The work done on the crate by the normal force of the plane on the crate is zero.

Consider two frictionless inclined planes as shown.

Both M₁ and M₂ are released at the same time.

1. Compare the speeds of the two masses when they reach the bottoms of their respective inclines.

M₁ is travelling faster than M₂.
M₂ is travelling faster than M₁.
M₁ and M₂ are travelling at the same speed.
It is impossible to tell.

2. Which mass gets to the bottom first?

M₁.
M₂.
M₁ and M₂ arrive at the same time.
It is impossible to tell.

You slam on your brakes in a panic and skid a certain distance down a straight and level road. If you had been travelling twice as fast, what distance would the car have skidded under the same conditions?

	Four times further.
	Two times further.
	The square root of two times further.
	It is impossible to tell.

	A force can only do work if it points in the same direction as the displacement.
	Only the component of a force parallel to the displacement does work.
	The component of a force perpendicular to the displacement does positive work.
	Only the net force on an object does any work.

	10 J.
	More than 10 J.
	Less than 10 J.
	It is impossible to tell.

	The work done on the object by gravity is zero.
	The gravitational PE of the crate is increasing.
	The work done by the net force acting on the crate is zero.
	The work done on the crate by the normal force of the plane on the crate is zero.

	M₁ is travelling faster than M₂.
	M₂ is travelling faster than M₁.
	M₁ and M₂ are travelling at the same speed.
	It is impossible to tell.

	M₁.
	M₂.
	M₁ and M₂ arrive at the same time.
	It is impossible to tell.

Physics 121 General Physics Concept Quizzes Chapter 7. Energy and Energy Transfer Chapter 8. Potential Energy

Physics 121 General Physics
Concept Quizzes
Chapter 7. Energy and Energy Transfer
Chapter 8. Potential Energy