A crate is being pushed across a rough floor surface. If no force is applied on the crate, the crate will slow down and come to a stop. If the crate of mass 50 kg moving at speed 8 m/s comes to rest in 10 seconds, what is the rate at which the frictional force on the crate takes energy away from the crate

Energy is being taken away at a rate of 160 J per second from the crate.

Explanation:

The only energy the crate has when it moves is kinetic energy. Friction takes this away at a specific rate. The total kinetic energy at the start is as follows:

Kinetic energy = 0.5 * m * V^2

Here m = 50 kg

V = 8 m/s

Kinetic energy = 0.5 * 50 * 8^2

Kinetic energy = 1600 J

This is also the total energy taken away by friction. We may divide this by the time to find out the rate of change of energy of the crate:

Rate of change of energy = 1600 / 10 = 160 J

Thus, energy is being taken away at a rate of 160 J per second from the crate.