A pendulum bob of mass 0.40 kg is released from rest at a vertical height of 0.75 m above its lowest position. After passing through its lowest position, the bob rises to a vertical height of 0.62 m on the other side.
The system contains the pendulum bob, Earth, the air and the pendulum support. No energy is transferred across the boundary of the system.
The gravitational field strength is 10 N kg-1.
Calculate the decrease in the gravitational potential energy of the pendulum bob between its release and its highest position on the other side.
Explain the energy changes that cause the pendulum bob to reach a lower height on the other side. Your answer should include what happens to the total energy of the system.