The pendulum in a clock gradually slows down and stops moving after a while. A student states that its loss of mechanical energy is evidence that energy is not always conserved.
Which two statements offer evidence that the clocks energy is conserved?
. Conservation of energy happens only when the parts of the clock are oiled to reduce friction.
. The pendulum stops moving because all of its mechanical energy has been transformed into thermal energy and sound energy.
. Conservation of energy occurs because the clocks matter is also conserved.
. Friction between its moving parts transformes some of the pendulums energy into other forms of energy.
