If a raindrop falls under the influence of the downward gravitational force and the opposing resistive force. Consider a drop of mass 1.00 g falling from a height 1.00 km. It hits the ground with a speed of `50.0 ms^(-1)`. (1) What is the work done by the gravitational force ? (2) What is the work done by the unknown resistive force ?

Explanation

The change in kinetic energy of the drop is
`Delta k = (1)/(2) mv^(2) - 0`
`= (1)/(2) xx 10^(-3) xx 50 xx 50 = 1.25 J`
where we have assumed that the droop is initially at rest .
Assuming that g is a constant with a value `10 m//s^(2)`, the work done by the gravitational force is ,
`W_(g) = mgh = 10^(-3) xx 10 xx 10^(3) = 10.0 J`