When a body moves on an inclined plane with a constant velocity, the work done on the body is zero.
Work is defined as the product of force and displacement in the direction of the force. In this case, the force acting on the body is the component of the force of gravity that is parallel to the incline (mg sinθ), where m is the mass of the body and g is the acceleration due to gravity. The displacement of the body is along the incline.
Since the body is moving with a constant velocity, the net force acting on it is zero. This means that the force of gravity is balanced by another force, such as friction or an applied force, that is equal in magnitude and opposite in direction. Since the net force is zero, no work is done on the body as it moves along the incline.
In other words, the work done by the force of gravity is exactly counteracted by the other force (friction or applied force) so that the body can maintain a constant velocity. Therefore, the work done on the body is zero in this situation.