Answer: Energy stored:A spring compresses and returns
to its original shape when released.An object lifted with a pulley drops
down when the rope is released.
Energy not stored:A boat travels through water
(and air) and doesn’t move
after stopping.A box is pushed and doesn’t
move after the pushing stops.
Explanation:
We store energy in a spring when we compress it. When we release the spring, it returns to its original shape. The stored energy changes into kinetic energy. When a pulley lifts an object, the object gains stored energy. This stored energy changes to kinetic energy when the rope is released. A boat moving on water doesn’t store energy. Its kinetic energy is transformed to thermal energy because of drag. For the same reason, pushing a box on a table against friction doesn’t store energy either.
