Rajasthan Police Constable Model Paper 4

CONCEPT:

• Work: Work is said to be done by a force when the body is displaced actually through some distance in the direction of the applied force.
• The SI unit of work is the joule (J).
• Since the body is being displaced in the direction of F, therefore work done by the force in displacing the body through a distance s is given by:W=

  →

  F

  .

  →

  s

Or, W = Fs cos θ

• Thus work done by a force is equal to the scalar or dot product of the force and the displacement of the body.

EXPLANATION:

• The SI unit of force is Newton (N) and the SI unit of displacement is the meter (m).

So the unit of work = Unit of force × unit of displacement = N.m

• Also, The SI unit of work is the joule (J). Thus option 4 is correct.

1 Joule = 1 N.m

NOTE: The commercial unit of energy is kilowatt-hour.