Potential Energy
Introduction
Potential energy is the stored energy of an object due to its position relative to other objects, stresses within itself, its electric charge, or other factors. The units for potential energy are joules (J) in the International System of Units (SI).
Types of Potential Energy
There are several types of potential energy, including gravitational potential energy, elastic potential energy, chemical potential energy, and nuclear potential energy.
Gravitational Potential Energy
Gravitational potential energy is energy an object possesses because of its position in a gravitational field. The most common example of gravitational potential energy is an object being lifted off the ground. When an object is raised vertically, work is done against the gravitational force.
Elastic Potential Energy
Elastic potential energy is energy stored in any object or material that can be stretched or compressed and then return to its original shape. Examples of objects that have elastic potential energy include springs, rubber bands, and bungee cords.
Chemical Potential Energy
Chemical potential energy is the energy stored in the bonds of chemical compounds. This energy can be released during a chemical reaction, often producing heat as a by-product (exothermic reaction). Examples of chemical potential energy include a battery, a piece of coal, or a log of wood.
Nuclear Potential Energy
Nuclear potential energy is the energy stored in the nucleus of an atom. It can be released during nuclear reactions (nuclear fission and nuclear fusion). The energy produced in nuclear reactions is much greater than that of chemical reactions because the binding energy that holds a nucleus together is greater than the energy that holds electrons to a nucleus.
Calculation of Potential Energy
The calculation of potential energy depends on the type of potential energy being considered.
Gravitational Potential Energy
The formula for gravitational potential energy is:
PE = mgh
where: PE is the gravitational potential energy, m is the mass of the object, g is the acceleration due to gravity, and h is the height of the object above the ground.
Elastic Potential Energy
The formula for elastic potential energy is:
PE = 0.5 * k * x^2
where: PE is the elastic potential energy, k is the spring constant, and x is the amount of compression or extension of the spring from its equilibrium position.
Conservation of Energy
The law of conservation of energy states that energy cannot be created or destroyed, only transferred or converted from one form to another. In terms of potential energy, this means that the total energy of an isolated system remains constant if the only forces doing work are conservative forces.