Power (College Board AP® Physics 1: Algebra-Based): Exam Questions

A carpenter pushes a box across a smooth wooden floor with her foot. She applies a force parallel to the displacement of the box, causing it to move at a constant speed . The coefficient of kinetic friction between the box and the wooden floor is .

Which of the following expressions describes the rate at which the carpenter does work on the box?

A Jack-in-a-box is composed of a toy mounted on a compressed spring that is released when the box is opened. The spring has a spring constant of and is compressed inside the box. The toy takes spring out of the box.

Which of the following is most nearly the power delivered to the toy by the spring?

A warehouse worker pulls a crate of mass along the floor with a coefficient of kinetic friction of using a rope applied at angle from the horizontal. As the worker pulls the crate, the tension in the rope is and they move the crate a distance of in a time of .

Which of the following is most nearly the average power delivered to the crate by the worker?

A constant force of is needed to move a sofa over a carpeted floor at a constant rate. The force is applied at an angle of from the vertical.

If, at a given moment, the sofa is moving at a speed of , which of the following is most nearly the instantaneous power delivered to the sofa?

A car of mass accelerates up a slope inclined at . If the car moves at a constant speed of while experiencing a resistive force of , which of the following is the instantaneous power output of the engine?

An object of mass floats in space. A force of is continuously applied to the object, causing it to accelerate at a constant rate. The object's initial velocity is measured from a nearby planet as having a magnitude of .

Which of the following is the instantaneous power applied to the object after 52 weeks?

A person pulls a crate along the floor with a rope. At time , the person is applying a force to the rope at an angle of to the floor.

Later, at time , the person changes the angle of the rope while applying the same magnitude force. The speed of the crate at is a factor of 1.5 smaller than the speed at and the instantaneous power is a factor of 6 smaller.

Which of the following statements most nearly describes how the angle of the rope has changed?

A pendulum bob of mass swings from a light string of length . When the bob is moving at a speed , its angular displacement from the vertical is . The string experiences tension force at this moment.

Which of the following shows the instantaneous power exerted by the tension force in the string and the weight of the bob?

Assume no air resistance.