Write a note on work done by a variable force.

Explanation

When the component of a variable force F ac!s on a body, the small work done ( dW) by the force in producing a small displacement dr is given by the relation
`dW = F cos theta dr` [ F cos ` theta ` is the component of the variable force F]
where, F and `theta` are variables. The total work done for a displacement from initial position `r_i` to final position `r_f` is given by the relation
` W = int_(r_i)^(r_f) dW = int_(r_i)^(r_f) F cos theta dr `
A graphical representation of the work done by a variable force is shown in figure given below. The area under the graph is the work done by the variable force.