Answer:
Explanation:
1. The mechanical energy transforms to thermal energy as the pendulum slows and eventually stops moving.
This statement is true: the mechanical energy is the kinetic and potential energy.
When the pendulum swings, it exchanges potential and kinetic energy: when the pendulum is at the highest altitude, the potential energy is maximum, and the kinetic energy is zero; when the pendulum is at the lowest altitude, the potential energy is zero and the kinetic energy is maximum.
Nevertheless, due to the friction with air, part of the energy is transformed into thermal energy (heat) all the time the pendulum is moving. At the end, all the mechanical energy is transformed into thermal energy, and the pendulum stops.
2. The mechanical energy disappears as the pendulum slows and eventually stops moving.
This is false. As per the law of conservation of energy the enery does not dissapear but transformed into other forms: mechanical energy can be transformed into thermal or sound energy, or other forms of energy.
3. The pendulum will continue moving at the same speed until someone stops it because energy cannot be destroyed.
This is false. The friction with air causes the conversion of mechanical energy into thermal energy, and the pendulum will stop enven in no one stops it.
4. The pendulum will slow down but will never stop moving because energy cannot be destroyed.
This is false. As explained above the pendulum will slow down and stop moving because the mechanical energy will transform in thermal energy.
