A body of mass 100 kg is at rest on a plane inclined at 20° to the horizontal. A force P is applied to pull the body up the plane, directed at an angle of 20° to the plane and is at 40° to the...

A body of mass 100 kg is at rest on a plane inclined at 20° to the horizontal. A force P is applied to pull the body up the plane, directed at an angle of 20° to the plane and is at 40° to the horizontal. If m = 0.2, calculate the value of P: (a) when the body is just about to move up the plane and (b) when the body is on the point of sliding down the plane.