When a pendulum is held high and taut and then is released, the pendulum begins to swing. What’s the correct order of the energy
transformations in this example? (PE stands for potential energy.)
gravitational PE → elastic PE → thermal energy
gravitational PE → kinetic energy → thermal energy
kinetic energy → elastic PE → thermal energy
kinetic energy → gravitational PE → thermal energy
thermal energy → gravitational PE → kinetic energy
gravitational PE → kinetic energy → thermal energy
Explanation:
In the absence of friction, the mechanical energy which is the sum of potential energy and kinetic energy remains constant. When the pendulum is held high and is motionless, it possesses gravitational potential energy. When it is released, potential energy converts to kinetic energy. At lowest point, the pendulum has kinetic energy only.
In the presence of friction, damping occurs. The motion of pendulum slows down and the energy dissipates as thermal energy.
