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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

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