Assertion (A): When the displacement is normal to the direction of force, the work done is zero.

Reason (R): Work done depends on the angle between force and displacement.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true but R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Both A and R are true and R is the correct explanation of A.

Explanation

Assertion (A) is true.

As,

Work done (𝑊) =$\vec𝐹$⋅$\vec𝑑$= Fdcosθ ………….(i)

Where

F = magnitude of force

d = displacement

θ = angle between force and displacement

If displacement is normal (perpendicular) to the force, then 𝜃 = $90^o$

$\Rightarrow$ cos $90^o$ = 0 $\Rightarrow$ W = 0

Reason (R) is true.

From (i) it is clearly visible that work done depends upon angle between force vector and displacement vector.

Hence, R is the correct explanation of A.