Question

how much work is done on a body of mass 1kg whirling on a circular path of radius 5cm

Answer 1

 work  done on a body of mass 1 kg whirling on a circular path of radius 5m is zero, because the direction of the displacement is in the direction of the tangent drawn at the position of the body of 1 kg mass to circle of the path of the motion and the force acting on the body to move it in the circular motion in the direction of the radius, So the angle between the radius(direction of the force acting) and the tangent( the direction of the displacement) is 900.
Work done = Force × Displacement × q, Where q = Angle between Force and Displacement
Work done = Force × Displacement ×Cos 90 0 (but Cos 90 0 =0)
Work done = Force × Displacement × 0
Work done = 0