EQ – How is life affected by energy? (Sound) S8CS2 (Habits of Mind) & S8CS8 (Nature of Science S8P4. Students will explore the wave nature of sound a. Identify the characteristics of mechanical waves. d. Describe how the behavior of waves is affected by medium (such as air, water, solids). e. Relate the properties of sound to everyday experiences. f. Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch 4/16/2018

Originate from vibrating objects. Sound Waves Originate from vibrating objects. The vibrating objects transfer this sound energy by direct contact with other matter (usually air). 4/16/2018 2

Sound Waves Sound waves are classified as mechanical waves and they require a medium to transfer the energy. The energy disturbance travels in concentric waves, spreading out from the source like ripples that spread out when a pebble is dropped in a puddle. Sound waves are compression or longitudinal waves. 4/16/2018 3

Physical Characteristics of a Compression or Longitudinal Wave Since sound is a longitudinal wave, it has the same characteristics previously studied: Wavelength = rarefaction to rarefaction or compression to compression;

Sound Waves Frequency (Pitch) – relates to speed (v = λ x f); number of vibrations per second 4/16/2018

Sound Waves Amplitude - amount of energy determines the loudness; NOT RELATED TO FREQUENCY OR WAVELENTH 4/16/2018

Speed of Sound The speed of sound depends on type of medium: Liquids and solids transmit sound waves better than gases The particles are closer together in liquids and solids making the transmission of energy easier 4/16/2018 7

Speed of Sound AND, the temperature of medium: Higher temperature -- faster speed Sound will travel slower in cold air on a winter’s day than it will travel in the warm air of a summer’s day Why do you think this is? 4/16/2018 8

Sound travels slower than light: Sound travels at 344 m/s through air at 20 C Light travels at 300,000,000 m/s Can you explain why the flash of a firework is seen before the sound of the firecracker explosion? 4/16/2018 9

Sound Wave Interaction Interference is ability of two more waves to combine and form a new wave. 4/16/2018

Sound Wave Interaction Constructive interference occurs when the compressions of two or more waves arrive at the same place at the same time. When this occurs, the compressions overlap and form a greater compression. As a result the sound will be louder. 4/16/2018

Sound Wave Interaction Destructive interference occurs when the compressions of one wave overlaps the rarefactions of another Wave thus decreasing the amplitude. 4/16/2018

Sound Wave Interactions http://id.mind.net/%7Ezona/mstm/physics/waves/interference/twoSource/TwoSourceInterference1.html http://www.colorado.edu/physics/2000/applets/fourier.html

Blowing into the instrument causes the reed to vibrate. Resonance (short & sweet) Resonance is the transfer of energy from one system to another; or in other words resonance occurs when one vibrating body causes another body to vibrate at its natural frequency. note: many musical instruments, especially stringed instruments, need something to increase the loudness of the sound i.e. guitar has a resonance chamber Ocean Sounds? Background noises cause the air inside the shell to vibrate and creates the sound of the ocean. Blowing into the instrument causes the reed to vibrate. 4/16/2018

Doppler Effect For sound waves, the Doppler effect is the apparent change in the frequency of a sound caused by the motion of either the listener or the source of the sound. 4/16/2018

THE END A special thanks to Pam McCann, Diane Goldsberry, and Linda Trawick for sharing their information and ideas! 4/16/2018