Question

A force is applied on a body of mass 20 kg moving with a velocity of 50 ms^-1 in 2 seconds. Calculate the work done by the body .

Answer 1

Solution :

Mass = 20 kg .

Velocity = 50 m/s .

Time = 2 s .

Find the displacement

$Velocity=\frac{displacement}{time}\\\\\implies 50m/s=\frac{displacement}{2s}\\\\\implies displacement=50m/s\times2s\\\\\implies displacement=100m$

Find the force applied

$Force=mass\times acceleration\\\\\implies Force=20kg\times \frac{velocity}{time}\\\\\implies Force=20kg\times \frac{50m/s}{2s}\\\\\implies Force=20kg\times 25m/s^2\\\\\implies Force=500kgm/s^2\\\\\implies Force=500N$

Find the work done

$Work\:done=force\times displacement\\\\\implies Work\:done=500N\times 100m\\\\\implies Work\:done=50000Nm\\\\\implies Work\:done=50000J\\\\\implies Work\:done=50kJ$

$\mathfrak{\underline{ANSWER}}$

$\huge\boxed{\green{50kJ}}$