Introduction to Energy

Scientists define energy as the ability to do work. Work occurs when a force is exerted on an object and causes the object to move. In this example, the energy from the football player is transferred to the training equipment. The energy of an object is measured in joules.

Power is the rate at which work is done, or energy is transferred. A lawn mower that can mow six lawns in an hour is more powerful than a lawn mower that can only mow two lawns in the same amount of time. Similarly, a gas stove that boils water in four minutes transfers energy at a faster rate than an electric stove that boils water in seven minutes. The gas stove is more powerful than the electric stove. Power is measured in joules per second, or watts.

There are two types of energy, potential and kinetic. The energy that is stored or exists because of the position of an object is called potential energy. A parked car and a stretched rubber band have potential energy. The energy of a moving object is called kinetic energy. Any object in motion has kinetic energy.