Final answer:
When holding a heavy weight stationary above your head, the work done on the weight is zero because there is no displacement of the object. However, the body is expending chemical energy to maintain the weight's position, which is not considered work on the object in the context of physics.
Step-by-step explanation:
When holding a heavy weight over your head without any movement, the work done is zero. Work is defined as a force applied over a distance; since there is no displacement while just holding the weight stationary, no work is performed on the object in terms of physics. However, your muscles are exerting a force to counteract gravity, and this action is using chemical energy from your body, but it does not equate to work being done on the object itself according to the scientific definition.
In physics, work is calculated as the product of force and displacement in the direction of the force. Since the weight is not moving upwards or downwards, the displacement is zero, making the work done also zero. The energy you are expending is simply maintaining the potential energy of the weight at that height due to gravity. If you were to lift the weight higher, you would be doing positive work and imparting additional potential energy to the object.