question_answer

  (a) The potential energy of a freely falling object  decreases  progressively.  What happens to its (i) kinetic energy, (ii) total mechanical energy? State the law on which your answer is based. (b) A household consumes 1 kWh of energy per day. How much energy is this in joules?

Answer:

   (a) (i) As potential energy decreases with decreasing height, the speed of the object will increase and hence its kinetic energy will increase. (ii) Total mechanical energy will remain constant. It is based on the law of conservation of energy which states that energy can neither be created nor be destroyed. It can only by transformed from one form to another.            (b)1kWh = 3.6x106J