Question

When does a force perform work?

Answer 1

Work is said to be done only when the force applied on a body makes the body move (i.e. if there is some displacement or motion occurred due that force).

Answer 2

• Displacement Occurs: The object on which the force is applied must move (displace) in response to the force.

• Component of Force Along Displacement: There must be a component of the applied force in the direction of the displacement.

Formula for Work:

Work = Force × Displacement × cos θ

θ is the angle between the force and displacement directions.

Key Points:

• If the displacement is zero, no work is done, even if a force is applied.
• If the force is perpendicular to the displacement (θ = 90°), no work is done because cos ⁡90°.