Energy is all around us. Energy can be classified as potential or kinetic. Potential energy is stored energy. Kinetic energy is moving energy. There are many types of potential and kinetic energies.
Mechanical energy is both kinetic and potential energy because it is the energy of motion and position. For example, a bike traveling up and down a hill sometimes has kinetic energy and sometimes has potential energy.
Sound energy is a type of mechanical energy because it is the energy of molecules vibrating. Vibration is a type of movement, so sound energy is kinetic mechanical energy.
When two objects collide, they push on the air molecules around them. The air molecules vibrate and push on the air molecules next to them. The sound energy moves away from the two objects in a wave. Each molecule bumps into the next molecule causing it to move. A sound wave is similar to fans doing the wave at a baseball game.
When the vibrations of sound energy enter our ears, they make the ear drum vibrate. The vibrations travel through the tiny bones of the middle ear to the inner ear. Thousands of tiny hair cells in the inner ear convert the vibrations into an electrical signal that is sent to the brain. The brain interprets the signals as sounds.
Sound energy moves at different speeds through different mediums. It moves the fastest through solids, slower through liquids, and the slowest through gases. The change in speed is why things sound funny to us underwater. Because sound energy is the energy of molecules vibrating, sound cannot travel through a vacuum. There is no sound in space.
Sound energy has low levels of energy, so it isn’t efficient to convert sound energy into different types of energy. Microphones and speakers convert sound energy into electrical energy and back into sound energy to amplify sound, but electrical energy must be added to the system.
It is amazing to think that everything we hear comes from microscopic molecules vibrating. Sound energy is all around us! Without it, we couldn’t hear music or talk with our friends. Sound energy is an important type of mechanical energy.