Question

In which of the following cases will the work done by a force be maximum:

When the angle between the direction of force and displacement is,

1. zero
2. ${90}^0$

Answer 1

If the direction of force applied is the same as the direction of motion of the object, then the work done is positive work done.

$Workdone\left(W\right)=Force\left(F\right)\times displacement\left(s\right)\cos \left(\theta \right)$

$W=F\times s\cos \left(\theta \right)$

$W=F\times s\cos \left(0^0\right)$

$\therefore W=F\times s[\cos \left(0^0\right)=1]$

1. The work done will be maximum when $\cos \left(0^0\right)=1$.
2. If the angle between the direction of force and displacement is ${90}^0$, then the work done is zero. As $\cos \left({90}^0\right)=0$.

Hence, work done by the force is maximum when the angle between the direction of force and displacement is zero.