Question

A. At what point in it's motion is the kinetic energy of the end of a pendulum greatest? b. At what point is the potential energy of a pendulum greatest?

Answer 1

`A.` Kinetic energy is defined as:

`=>E_k = 1/2 mv^2`

Since the mass of the pendulum bob won't change, the only way for kinetic energy to change is for the speed of the pendulum to change. Kinetic energy is highest when the velocity is the highest. This occurs at the bottom of the pendulum.

`B.` If kinetic energy is highest at the bottom of the pendulum, then that is where potential energy is the lowest. So potential energy would be highest when the pendulum is at its highest point on either side of its motion where it is stationary for an instant. This is the point where all kinetic energy has been converted to potential energy (`E_k = 0` since `v = 0`).