A raindrop of mass 1.00 g falling from a height of 1 km hits the groun

1.	A raindrop of mass 1.00 g falling from a height of 1 km hits the ground with a speed of 50 m s–1. Calculate (a) the loss of P.E. of the drop. (b) the gain in K.E. of the drop. (c) Is the gain in K.E. equal to loss of P.E.? If not why. Take g = 10 m s-2
Answer» (a) Loss of PE = mgh = 1 x 10^-3 x 10 x 10^-3 = 10J (b) Gain in KE = (1/2)mv² = (1/2) x 10^-3 x 2500 = 1.25J (c) No, because a part of PE is used up in doing work against the viscous drag of air.

A raindrop of mass 1.00 g falling from a height of 1 km hits the ground with a speed of 50 m s–1. Calculate (a) the loss of P.E. of the drop. (b) the gain in K.E. of the drop. (c) Is the gain in K.E. equal to loss of P.E.? If not why. Take g = 10 m s-2

Answer»

(a) Loss of PE = mgh = 1 x 10^-3 x 10 x 10^-3 = 10J

(b) Gain in KE = (1/2)mv² = (1/2) x 10^-3 x 2500 = 1.25J