Today is Tuesday, May 7th, 2013 Homework: Homework Packet Due this Friday Finish Reading Ch. 14 by Friday Ch. 13-14 Combined Test on Monday, May 13th Warm UP: Discuss with your shoulder partner: What are some ways that you interact with light and sound in your daily lives?

Goal for Today SWBAT demonstrate the ability to recognize various forms of energy by exploring how sound energy behaves and transfers.

Sound…. Sound is a vibration that spreads from its source Must travel through a material; molecules vibrate in a pattern A basic sound wave: Compressions – areas where particles are very close together Rarefactions – areas where particles are far apart Wavelength – distance between crests Frequency – measure of how fast particles are vibrating. Greater frequency, higher pitch the sound Pitch is related to frequency Decibels – units that measure sounds loudness Volume is related to amount of vibration. Louder the sound, the higher the crest (or the energy squeezes particles closer together)

Place your hands on your vocal chords. Make a sound Place your hands on your vocal chords. Make a sound. Do you feel it vibrate Vocal chords cause the air that passes through to vibrate Where else do you see vibrations when sound is made? Sound energy can travel through solids, liquids and gases. Can’t travel through a vacuum. Why?

When sound energy reaches the border of a new material, 3 things can happen: 1) bounce back, 2) be absorbed, 3) pass through Sounds travels at different speeds in different materials and when conditions of a material change Echo results when sound is reflected back In a soundproof room, sound is bounced and absorbed. Each time sound bounces, material vibrates and some of the energy is turned to thermal energy For sound to be heard, the energy from the vibrations must be transferred (through the air to your ear to your eardrum)

Closing it up…. Let’s see what Tim and Moby have to say….