A body of mass 0.1kg released from a height of 50m reaches the ground with a velocity of 10ms^–1. The work done against air resistance is (g=10 m/s²)

Given,

mass of the body = 0.1kg

height h =50m

velocity = v= 10m/s

We know that,

potential energy = mgh

$$\begin{gathered} PE=0.1\times 10\times 50 \\ PE=50J \end{gathered}$$

similarly kinetic energy,

$KE=\frac{1}{2}m{v}^2$

$KE=\frac{1}{2}\times 0.1\times 10\times 10=5J$

$Work done = PE-KE = 50J-5J= 45J$

Hence the correct answer is 45J.