In the presence of friction, mechanical energy alone is not conserved, although total energy remains conserved.

The coefficient of restitution for a perfectly elastic collision is:

Two bodies of equal mass undergo a one-dimensional elastic collision, with one initially at rest. After the collision:

In a perfectly inelastic collision, which quantity is conserved?

Instantaneous power in terms of force $\vec F$ and velocity $\vec v$ is:

A man does 1000 J of work in 10 s. His average power is: