A force F acts on a body such that it is always at an angle of `45^@` to the direction of motion. The body moves in a circle and covers a semicircle of radius R. What is the work done by the force F?

Explanation

The work done by the force can be found by taking the component of the force acting along the direction of displacement and calculating the displacement caused by this component. The component of the force acting along the direction of motion of the body would be `F cos 45^@`.
The point of action of force would be `45^@` to the direction of motion of the body.
The frame would be the frame of the circular motion.
The displacement would be parallel to the direction of application of the force.
The displacement in this circular motion would be `piR`. Therefore, work done would be `Fcos 45^@ (piR)=piFR//sqrt2`