Free Practice Quiz Question List

6 - Work, Energy, and Conservation of Energy Online Quiz Questions

Use this free practice quiz with 20 questions to review 6 - Work, Energy, and Conservation of Energy, test your knowledge, and prepare for your next test or exam.

20 questions

Choose one

1 point

A constant force acts on an object while the object moves through a displacement at an angle of $60^\circ$ to the force. Which statement correctly describes the work done by the force?

A
The force does negative work because it is not parallel to the displacement.
B
The force does positive work because its component along the displacement is positive.
C
The force does zero work because the force is not parallel to the displacement.
D
The force does positive work only if the object speeds up.

True or false

1 point

True or false: Work is a scalar quantity, so it has no direction even though it can be positive or negative.

A
True
B
False

Written response

1 point

What is the name of the theorem stating that the net work done on an object equals its change in kinetic energy?

Fill in the blank

1 point

Complete the statement: The net work done on an object equals the change in its energy.

Choose one

1 point

A force varies with position along the $x$ -axis. Which expression gives the work done by this force from $x_A$ to $x_B$ ?

A
$W=Fd$ for the largest force value
B
$W=\frac{1}{2}mv^2$
C
$W=\int_{x_A}^{x_B}F_x(x)\,dx$
D
$W=mg(y_f-y_i)$

True or false

1 point

True or false: Changing the reference level for gravitational potential energy changes the calculated potential-energy values but does not change the physical predictions.

A
True
B
False

Choose all

1 point

Select all properties that characterize a conservative force.

A
Its work depends only on the initial and final positions.
B
Its magnitude must be constant everywhere.
C
It always does positive work.
D
Its work around any closed path is zero.

Written response

1 point

A block has an initial kinetic energy of $50\text{ J}$ and slides across a level surface while friction does $-18\text{ J}$ of work. What is the block's final kinetic energy? Enter the value in joules.

Fill in the blank

1 point

Complete the statement: The energy stored in an ideal stretched or compressed spring is called energy.

Choose one

1 point

A skier moves downhill while kinetic friction does negative work. Which equation correctly accounts for the energy change?

A
$K_i+U_i+W_{\text{nc}}=K_f+U_f$
B
$K_i+U_i=K_f+U_f$ regardless of friction
C
$W_{\text{nc}}=K_i+K_f+U_i+U_f$
D
$K_i-U_i+W_{\text{nc}}=K_f-U_f$

Choose all

1 point

Select all statements that correctly match an energy method to a situation in which it is appropriate.

A
Use the work–energy theorem when the net work is known and the desired result is a change in speed.
B
Use mechanical-energy conservation even when friction does work, without adding any extra term.
C
Use mechanical-energy conservation when the important forces are conservative and the initial and final states are specified.
D
Use the work–energy theorem only when the object's acceleration is constant.

Open ended

1 point

A ball is released from rest at height $h$ above the ground. Air resistance is negligible. Derive an expression for its speed immediately before it reaches the ground and explain whether the result depends on the ball's mass.

Choose one

1 point

An ideal spring has spring constant $200\text{ N/m}$ and is compressed by $0.20\text{ m}$ . As it returns to equilibrium, how much work does the spring force do?

A
$-8.0\text{ J}$
B
$-4.0\text{ J}$
C
$+4.0\text{ J}$
D
$+8.0\text{ J}$

Choose one

1 point

A box is pushed horizontally and slides across a level floor. Of the contact forces listed, which force is perpendicular to the box's horizontal displacement and therefore does zero work?

A
The applied pushing force
B
The normal force from the floor
C
The kinetic-friction force
D
A horizontal tension force

Choose one

1 point

A $4.0\,\text{kg}$ cart moving at $2.0\,\text{m/s}$ experiences $12\,\text{J}$ of net work. What is its final speed?

A
$2.0\,\text{m/s}$
B
$2.8\,\text{m/s}$
C
$3.0\,\text{m/s}$
D
$3.2\,\text{m/s}$

Choose one

1 point

A $0.10\,\text{m}$ compressed ideal spring with spring constant $200\,\text{N/m}$ launches a block on a frictionless horizontal surface. How much kinetic energy does the block gain when the spring returns to equilibrium?

A
$1.0\,\text{J}$
B
$2.0\,\text{J}$
C
$10\,\text{J}$
D
$20\,\text{J}$

Choose one

1 point

A block slides on a level surface with an initial kinetic energy of
$40\,\text{J}$ . Friction is the only force doing nonzero work on the block, and friction does
$-15\,\text{J}$ of work. What is the block's final kinetic energy?

A
$15\,\text{J}$
B
$25\,\text{J}$
C
$40\,\text{J}$
D
$55\,\text{J}$

True or false

1 point

True or false: If a force is conservative, the work it does between two points is independent of the path taken between those points.

A
True
B
False

Written response

1 point

A $2.5\,\text{kg}$ object moves from height $2.0\,\text{m}$ to height $1.5\,\text{m}$ . Using $g=10\,\text{m/s}^2$ , what is the change in its gravitational potential energy? Enter the value in joules, including its sign.

Written response

1 point

A cart has an initial kinetic energy of $40\,\text{J}$ . An applied force does $10\,\text{J}$ of work, while friction does $-18\,\text{J}$ of work. What is the cart's final kinetic energy? Enter the value in joules.