Engine in thrust. Particularly notable kinds of engines include: Engine An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines burn a fuel to create heat which is then used to do work. Internal combustion engines are heat engines that burn fuel in a combustion chamber to extract work from the pressure of expanding gases. Electric motors convert electrical energy into mechanical motion; pneumatic motors use compressed air; and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces
Potential energy the negative of this scalar field so that work by the force field decreases potential energy, that is In this case, the application of the del operator to the work function yields, and the force F is said to be "derivable from a potential." This also necessarily implies that F must be a conservative vector field. The potential "U" defines a force F at every point x in space, so the set of forces is called a force field. Given a force field F(x), evaluation of the work integral using the gradient theorem can be used to find the scalar