A brick weighing `4.0 kg `is dropped into a `1.0m` deep river from a height of `2.0m` Assuming that `80%` of the gravitational potential energy is finally converted into thermal energy, find this thermal energy in calorie.

Answer

A, B, C

Explanation

Total P.E. `= 4 xx 10 xx 3 = 120J`
Energyutilized `= 120 xx (80)/(100)= 96J`
`= (96)/(4.2) = 22.857 cal`
`23 cal`