Question

A body of mass $4kg$ is thrown upward with a velocity of $40m/s$ it comes to rest after attaining maximum height of $30m$. How much energy is lost due to air friction?

• A. $2000J$
• B. $118J$
• C. $1800J$
• D. $1810J$

Answer 1

Answer: (A)

Initial energy of body $K.E=\frac{1}{2}m{v}^2=\frac{1}{2}\times 4\times 40\times 40$
=3200 J
At highest point, energy possesses in the form of
potential energy $P.E$ mgh $=4\times 10\times 30=1200J$
Energy lost due to air friction is
$\Delta E=E_i-E_f$
$\Delta E=3200-1200$
$\Delta E=2000J$