Question

Right click and open the Pendulum Lab pHet in a different window. Click on the
Energy Lab.
Start the pendulum at a height of 2.0 meters and release it without pushing.
Describe how the potential energy and kinetic energy change as the pendulum swings back and forth. Explain why these changes occur in 2-3 sentences.

Answer 1

At release (2.0 m) gravitational potential energy is at a maximum and kinetic energy is zero; as the pendulum falls the potential energy decreases and is converted into kinetic energy, which peaks at the lowest point. On the way back up kinetic energy is converted back into potential until the bob momentarily stops at the next peak; this happens because gravity does work converting between PE and KE and (neglecting friction/air resistance) the total mechanical energy stays constant.