(i) the loss in potential energy of the body,

(ii) the total energy possessed by the body at any instant? (Take g = 10 ms^-2).

Solutions:

According to the question –

(i) Mass of the body is M = 5 kg

Expression for the potential energy is mgh, for height h = 10m we have –

PE = 5 × 10 × 10 = 500 J

Similarly, Potential energy at height 4 m = mgh

= 5 × 10 × 4 = 200 J

Then the loss in potential energy becomes –

 (500 – 200) J = 300 J

(ii) From the definition of total energy, we know that –

For free fall, the total energy possessed by the body at any instant remains constant. It is equal to the sum of P.E and K.E

Therefore, at height 10 m, K.E is zero

Hence, total energy = P.E + K.E

Total energy = 500 + 0 = 500 J