A force F acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of force. - Noon Academy

A force F acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of force.

Class 10 | ICSE | Physics | Selina | Work Energy

A force F acts on a body and displaces it by a distance S in a direction at an angle θ with the direction of force.

(a) Write the expression for the work done by the force.

(b) What should be the angle between force and displacement so that the work done is

(i) zero,

(ii) maximum?

Solutions:

(a) W = F S cos θ

This expression gives the work done when force is at an angle to the direction of displacement.

(b) (i) The angle between force and displacement for zero work done should be 90⁰ as cos 90⁰ = 0 .

W = F S cos 90⁰ = FS × 0

Therefore, W = 0

(ii) The angle between force and displacement for maximum work done should be 0⁰ as cos 0⁰ = 1.

Then, W = FS cos 0⁰ = FS × 0

W = FS

i

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