Physics in Motion: Work & Energy

In physics, when is work done on an object?

• When a force is applied to an object, regardless of movement.

• When an object moves at a constant speed.

• When a force displaces an object.

• When an object is held stationary against a force.

What is the standard unit for work in physics?

• Newton (N)

• Meter (m)

• Joule (J)

• Watt (W)

A person lifts a box upwards. What type of work is being done by the applied force?

• Negative work

• Positive work

• Zero work

• No work can be determined without more information.

When is zero work done on an object?

• When the force applied is very small.

• When the object moves at a very high speed.

• When the force and displacement are perpendicular to each other.

• When the object is accelerating.

When performing a sit-up, if a person starts and ends in the same position, what is the net work done by the applied force during the complete motion (up and down)?

• Positive

• Negative

• Zero

• Depends on the speed

A 300.0 kg tackle sled is accelerated at 0.25 m/s^2 by football players over a distance of 15.0 m. Assuming negligible friction, what is the work done on the sled by the players?

• 75 J

• 4500 J

• 1.13 x 10^3 J

• 11.3 x 10^2 J

Which statement accurately describes the Law of Conservation of Energy?

• Energy can be created but not destroyed.

• Energy is never created nor destroyed, only transferred or transformed.

• Energy can be destroyed but not created.

• Energy is always converted into heat.

In physics, what defines a "system"?

• Any object that is moving.

• A collection of objects in a particular area that you want to study.

• A closed environment where no energy can enter or leave.

• The entire universe.

What is 1 important thing to remember about work?

What is 1 important thing to remember about energy?