In which of the following case the work done by a force will be maximum: when the angle between the direction of force and direction of motion is $0^\circ$ or $90^\circ$?
Answer
Work done will be maximum when angle between the direction of force and direction of motion is 0° because,
$\text{W} =\text{F}\cos\theta\times\text{s}.$
And, $\cos\theta\ 0^\circ=1$ and $90^\circ=0$
A load of $100\ kg$ is pulled up by $5\ m$. Calculate the work done. $(8 = 9.8\ m/s)$
Answer
Mass $= 100\ kg$
Height $= 5\ m$
g $= 9.8\ m/s^2$
P.E.$ = m \times g \times h$
$= 100 \times 5 \times 9.8 = 4900\ J$
Work done is equal to PE acquired by the body.