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

Figure 1

A microlight is a small airplane powered by a gasoline engine. Figure 1 shows the flight path of a short horizontal training flight, AB, which has a displacement of .

On its outbound journey, the resultant velocity of the microlight is at an angle west of due north. The work done by the engine is over it's flight path AB.

Derive an expression for the force exerted by the engine of the aircraft on its outbound journey as it travels at speed . Express your answer in terms of , , and . Begin your derivation by writing a fundamental physics principle or an equation from the reference booklet.

A box of mass is pushed across a rough wooden floor with a constant force applied parallel to the displacement of the box, such that the power delivered to the box maintains a constant speed .

Determine an expression for the magnitude of the coefficient of kinetic friction . Express your answer in terms of , , and physical constants as appropriate.

A crate of mass is pulled along a rough horizontal surface using a rope attached at an angle with respect to the displacement of the crate, where . The crate is displaced by an amount in time at speed by the rope with a constant tension force . The coefficient of kinetic friction between the crate and the surface is .

Determine an expression for the average power delivered by the rope during the crate's period of motion. Express your answer in terms of , , , , , and physical constants as appropriate.

A container of mass is pulled up a incline of angle with respect to the horizontal, by a chain attached to the container and parallel to the incline. The coefficient of kinetic friction between the container and the inclined surface is . At a specific instant , the container is moving with speed and acceleration .

Determine an expression for the instantaneous power delivered by the rope at time . Express your answer in terms of , , , , , and physical constants as appropriate.