In order to accomplish work on an object there must be a force exerted on the object and it must move in the direction of the force. ... For the special case of a constant force, the work may be calculated by multiplying the distance times the component of force which acts in the direction of motion.
Answer:
It won't let me type this for some reason but here it is.
I would say mass lost by nuclear collisions. The mass defect is the mass difference between the mass of an atomic nucleus and the sum of the mass of its constituent particles. It equals the energy given off in the formation of the nucleus.