Question

A pendulum has 540 J of potential energy at the highest point of its swing. How much kinetic energy will it have at the bottom of its swing?

Answer 1

If it doesn't lose any energy to friction in the pivot or air resistance, and nobody touches it while it's swinging, then ...

-- the energy it has is constant, and never changes

-- it's all potential energy at the highest point of the swing

-- it's all kinetic energy at the lowest point of the swing

-- it's part potential and part kinetic anywhere between the highest and lowest points.

The pendulum in this question has 540J of potential energy at the highest point, and 540J of kinetic energy at the lowest point.

Answer 2

The answer is 540 J because there is no energy lost and there is no potential energy at the height of 0.