Work and energy are measured in the same units. People often confuse energy, power, and force. Force is a push or a pull on an object or body. The amount of work is determined by the strength of the force used and the distance through which it moves. Power measures the rate at which work is done.
All human life depends upon the energy in the universe.
Most of the energy on earth comes from the sun. It travels from the sun to the earth in the rays that the sun gives off. The sun's rays are needed so that plants can make food. The food that plants make is the food on which all the animals in the world depend in order to live. Animals and human beings use the energy found in food to operate their bodies and muscles.