Question

In order to get minimum work, the angle between force and displacement should be $90°$.

• A. True
• B. False

Answer 1

The correct option is A True

1. Work is said to be done when a force is applied to a body, such that the force displaces the body from its initial position.
2. The formula for work done in the direction of force is written as $W=F·S$, where $W$ is the work done, $F$ is the force applied and $S$ is the displacement caused by the force.
3. If the direction of the body changes, such that the work done is in a direction different from that of the force applied, then the work done is given by $W=FS\cos \theta$ , where $W$ is the work done, $F$ is the force applied, $S$ is the displacement caused by the force and $\theta$ is the angle between the direction of force and displacement.
4. If the angle between the force and displacement is$90°$, then the work done will be $W=FS\cos 90°$, and the value of $\cos 90°=0$, so the work done will be zero.
5. Therefore, work done is minimum when the angle between force and displacement is $90°$

Hence, the given statement is true.