Energy

Energy comes in many different forms including chemical, nuclear, radiant, thermal, potential, kinetic, and even mass. Potential and kinetic energy are forms of mechanical energy. Energy can be changed from one form to another, but in each transformation some energy is always lost to the surroundings, usually in the form of heat.  Efficiency measures the effectiveness of energy transformations. A careful accounting of all the inflows and outflows of energy during any transformation will reveal that the total amount of energy remains precisely the same. This is known as the law of conservation of energy. Gravitational potential energy is the energy an object has due to its position in a gravitational field and can be calculated by multiplying the mass times the acceleration of gravity times the height above a specified zero height. This relationship can be shown in equation form as PE=mgh). Kinetic energy is energy of motion and is calculated as one half the mass times the speed squared.  This relationship can be shown in equation form as KE=½ mv².