One model of tennis ball launcher has advertised that it is capable of imparting 15,000 J of kinetic energy to a 0.5 kg ball initially at rest. A student carefully measures the compression of the spring to
be 0.10 m. What is the elastic energy stored in the spring?

energy can be converted from one form to another, but it cannot be created or destroyed in ordinary chemical or physical means. do not understand what you are asking but hope this

the duration of a photographic flash is related to an rc time constant, which is 0.100 μs for a certain camera.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.