Question

3. Describe the energy transformations which occur
i. At a power station which uses coal as its fuel
ii. When a boy shoots a stone from a catapult to hit a target.

Answer 1

i.  The furnace heat converts boiler water to steam, which is then used to spin turbines that turn generators. Thus chemical energy stored in coal is converted successively into thermal energy, mechanical energy and, finally, electrical energy. 

ii. When the stone is released, the potential energy is transformed suddenly as the kinetic energy of motion of the projectile. When the projectile hits a target, the kinetic energy is used to do the work of crumbling a target.

Eventually all of this energy is dissipated as heat energy.