What is work in physics?

What is work?

Scalar product of force and displacement is called work.

$$ W = \vec{F}.\vec{S}\cos \theta $$

Work is a scalar quantity. The dimensional formula of work is [ M1L2T-2 ]. SI unit of work is joule. CGS unit of work is erg.

Relation between joule and erg is
1 joule = 107 erg.

In terms of rectangular components, work is
W = x Fx + y Fy + z Fz

Types of work

Positive work

If angle between \(\vec{F}\) and \(\vec{S}\) lies between 00 and 900, then work done is positive.

Negative work

If angle between \(\vec{F}\) and \(\vec{S}\) lies between 900 and 1800, then work done is negetive.

Negative work

The work done is zero, if

  • there is no displacement
  • no force is acting on the body
  • angle between \(\vec{F}\) and \(\vec{S}\) is 900