Question

In angle in between the direction of applied force and displacement, for maximum work should be

• A. 90°
• B. 45°
• C. zero
• D. 30°

Answer 1

The correct option is C

zero

Explanation for the correct option

C: zero

Work done is expressed as the product of force and distance moved in the direction of the force.
W = Force x displacement x angle between force and displacement.

W = F x s x cos ∅

When ∅ = 0°, cos 0° = 1

W = F x s x 1

W = Fs

Explanation for the incorrect options

A: 90°
W = F x s x cos ∅

When ∅ = 90°, cos 90° = 0

W = F x s x 0

W = 0
B: 45°

W = F x s x cos ∅

When ∅ = 45°, cos 45° = $\frac{1}{\sqrt{2}}$ = 0.707

W = F x s x 0.707

W = 0.707 Fs
D: 30°

W = F x s x cos ∅

When ∅ = 30°, cos 30° = $\frac{\sqrt{3}}{2}$= 0.866

W = F x s x 0.866

W = 0.866 Fs

Hence, for maximum work angle between the direction of applied force and displacement must be zero.