wheel and axle — lifting machine comprised of a rope attached to a wheel such that applying a torque to the wheel winds the rope onto the axle. One of six types of simple machines.

work — form of energy equal to one newton of force exerted for one meter in the direction of the force. Measured in joules (J).

work function — energy needed to liberate an electron from a metal atom in the photoelectric effect.

work–energy theorem — change in the kinetic energy of an object equals the net work done on it.


x-rays — high frequency form of electromagnetic radiation.


zeroth law of thermodynamics — if two systems are in thermal equilibrium with a third system, then they are also in thermal equilibrium with each other. The implication of the zeroth law is that no heat will flow between two objects at the same temperature.

Previous Page Next Page861