Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take g constant with a value 10 m/s2. The work done by the (i) gravitational force and the (ii) resistive force of air is :
Answer & explanation
Correct answer: option 1
According to work energy theorem
wg + wR = \(\frac{1}{2}mv^2\)
wg = mgh
=10-3 x 10 x 103
= 10J
10 + wR =\(\frac{1}{2}\) x 10-3 x 50 x 50
10 + wR = 1.25
wR = -8.75J