Power through MoveMent Have you ever heard someone describe a person by saying he or she has a lot of energy Usually when someone says that they are talking about a person who moves around a lot It’s a good description because things and people need energy to move Energy is another word for power It makes things move or work and makes living things grow The shaking movement of a jackhammer produces sound energy The sound is very loud 4
Energy can be divided into two categories potential energy and kinetic energy Potential energy is power that is stored to use later Kinetic energy is power in action or moving energy There are many different Sound waves are invisible as they travel through the air from the source of a sound Vocabulary Something that vibrates has a shaking movement kinds of energy such as electricity heat and light Sound energy is made when an object or part of an object vibrates The vibrations move the air around it to make sound waves These are what we hear 5
have You heard When a dog barks the sound travels through the air and is received by a human ear All sounds travel in the same way They start at a source such as a bell that is rung or an object that is hit A medium such as air carries the sound waves Finally a receiver detects the sound Your receiver is your ear The human ear has three parts Each part has its own job The outer ear collects sound waves and contains 6
Sound waves move through each of the three parts of the ear before they can be heard the eardrum The eardrum vibrates when the waves hit it The middle ear sends the vibrations to the inner ear over three small bones Finally the vibrations go through a fluid in the inner ear making waves that send a sound signal to your brain Sound waves aren’t like waves in the ocean though They bend in and out quickly to push and pull the air around them This movement makes the sounds we hear Compare and Contrast How are the outer ear middle ear and inner ear alike How are they different 7
