FORMS OF ENERGY

Although there are many ways to classify energy, we will discuss eleven forms of energy. The first three forms of energy are related to the energy of motion associated with moving objects, atoms, and molecules.

MECHANICAL ENERGY OF MOTION:

Moving objects exhibit mechanical energy of motion, also called kinetic energy. A ball thrown through the air or a car travelling down a road has mechanical energy of motion.

THERMAL ENERGY:

Energy of motion occurs within an object as its atoms and molecules vibrate randomly. Thermal energy is the unorganized energy of motion of vibrating objects too small to see. The faster the atoms and molecules in a substance vibrate, the more thermal energy the substance has and the higher its temperature.

SOUND ENERGY:

When atoms and molecules vibrate in an organized manner, their vibrations may travel as a wave. Sound is the transmission of vibrations through a solid, liquid, or gas by vibrating atoms or molecules. When sound waves reach our eardrums, the energy in the sound waves causes our eardrums to vibrate. Our brains interpret the vibrations as sounds.

Matter contains positive and negative charges. Forms of energy that result from the forces between these charges are called electromagnetic energy. We can distinguish three forms of electromagnetic energy.

ELECTRICAL ENERGY:

Electrical energy results from the forces between charged particles. These electrical forces exist between charged particles at rest and in motion.

MAGNETIC ENERGY:

Charges moving within some types of materials produce magnetic forces. These magnetic forces are in addition to the electrical forces between moving charges. Magnetic materials are called magnets and attract or repel one another due to their magnetic forces. A coil of wire with charges moving through it acts like a magnet and is called an electromagnet.

RADIANT ENERGY:

While vibrations of matter produce thermal and sound energy, radiant energy results from vibrations of charges. Radiant energy is another name for waves of electromagnetic energy. For example, the sun’s energy is transported to Earth as waves of radiant energy. Radio waves, microwaves, infrared radiation, light waves, X-rays and cosmic rays are all waves of radiant energy.

Stored energy, which can be used to do work, is called potential energy. We consider five types of potential energy.

GRAVITATIONAL POTENTIAL ENERGY:

When a rock is raised above the Earth and released, the gravitational attraction between the rock and the Earth causes the rock to fall to the ground. A raised object has gravitational potential energy.

STRAIN POTENTIAL ENERGY:

If we stretch or compress a spring and release it, the spring moves back toward its original length. The stretched or compressed spring has strain potential energy because it has the potential to move.

CHEMICAL POTENTIAL ENERGY:

Chemical potential energy exists because atoms and molecules can take in or give off energy when their chemical bonds are formed or broken.

ELECTRICAL POTENTIAL ENERGY:

Electrical potential energy is stored when positive and negative electric charges are separated. The amount of stored energy depends on the number of separated charges and the distance they are separated.

NUCLEAR ENERGY:

In nuclear reactions, energy is given off or taken in by atomic nuclei. Energy is available from the nuclei of atoms that are radioactive and undergo nuclear changes.