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What is the expression of work for three different situations for force and displacement?

Answers (1)

  • Work done by a constant force-The scalar product of the force vector (\underset{F}{\rightarrow}) and the displacement vector (\underset{S}{\rightarrow})

                 w = \underset{F.}{\rightarrow}\underset{S}{\rightarrow}

  • work done by the variable force is given by

                                           W=\int \vec{F}\cdot \vec{ds}

           Where \vec{F} is a variable force and \vec{ds} is a small displacement. 

 The area under the force-displacement curve with the proper algebraic sign represents work done by the force.

Work done by the frictional force :

  •   is zero:  When the force applied on a body is insufficient to overcome the friction.

  •  is negative: When the force is large enough to overcome the friction

  •  is positive: When force is applied on a body, which is placed above another body, the work done by the frictional force on the lower body

           may be positive.

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Safeer PP

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