A raindrop of mass 1.00 g falling from a height of 1m hits the ground with a speed of 50`ms^(-1) ` Calculate
(a) the loss of PE of the drop
(b) the gain in KE of the drop
( c ) Is the gain in KE equal to loss of PE ? If not why ?
Take,` g =10 ms^(-2)`

Explanation

m = 1.00 g
` = 1xx10^(-3) kg`
h = 1 km = `10^(3)` m
` g = 10 m//s^(2)`
`v = 50 m//s `
(a) Loss in PE = mgh
`= 1xx 10^(-3) xx10 xx10^(3)`
= 10 J
(b) Gain in KE ` = 1/2 mv^(2)`
` 1/2 xx1xx10^(-3) xx(50)^(2)`
`=1/2 xx10^(-3) xx2500`
`= 1.250 J `
No , gain in KE is not equal to the loss in its PE , because a aprt of PE is used in doing work against the viscous drag of air .