A force `vecF=(-yhati+xhatj)N` acts on a particle as it undergoes counterclockwise circular motion in x-y plane in a circle of radius 4 m and with the centre at origin. If the work done by the force when the particle undergoes one complete revolution is (assume x,y are in m) `4pi lambda` joule then calculation `lambda`.

Explanation

`W=intF.dvecr=vecF.[Rdtheta(-sin thetahati+cos thetahatj)]`
`R^(2)int_(0)^(2x)dtheta`