Energy for Life

What Are Kinetic and Potential Energy?

Kinetic and Potential Energy

Energyglossary term (opens in a new window) exists in a variety of forms of kinetic and potential energyglossary term (opens in a new window). Organisms survive by converting energy from one form to another.

Kinetic energy is the energy any object has because it is moving. Objects can have kinetic energy regardless of their mass. Vibrating atoms have kinetic energy because they are moving. A running elephant also has kinetic energy. Energy from food is converted by the elephant’s muscles to make it move and give it kinetic energy. Kinetic energy is defined as the work needed to move a body of a given mass to its final velocity, or speed in a given direction.

Thermal energyglossary term (opens in a new window) is a term used to refer to heat generated by the kinetic energy of atoms and molecules. Atoms and molecules are in random constant motion. Temperature is a measure of this motion. Molecules moving more quickly have greater thermal energy than molecules moving more slowly.

Potential energy is the energy in a body or a system based on its position or configuration—it is stored energy. Potential energy exists in a number of forms. These include chemical potential energy, gravitational potential energy, and mechanical potential energy.

Chemical potential energy or chemical energyglossary term (opens in a new window) is the energy that is stored in the bonds between atoms. Chemical energy is released or absorbed during chemical reactions. When bonds are broken in chemical reactions, energy is absorbed. When bonds are made in a chemical reaction, energy is released. The balance of energy between bonds being broken and bonds being formed determines whether a chemical reaction releases or absorbs energy. Organisms store energy as chemical energy. Food compounds, like glucose, starch, or fats, contain a lot of chemical energy in their molecules. When cells metabolize food during cellular respirationglossary term (opens in a new window), they react these compounds in the presence of oxygen. This releases energy. Initially they may store some of the released energy as chemical energy in other “high energy” molecules. One of these molecules is adenosine triphosphate (ATP). This stored chemical energy is then readily available to do work within the cell. Chemical energy is required for all life processes.

Energy can be stored in other ways. A ball at the top of a hill has potential energy because of its position in relation to the center of the Earth. If the ball rolls down the hill, this gravitational potential energy is converted to kinetic energy. Stretched or compressed objects, like springs or rubber bands, can also store energy. This mechanical potential energy is converted to kinetic energy when the force holding them in position is released.