P H Y S I C S Chapter 7: Waves and Vibrations Section 7C: Wave Properties and Sound.

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P H Y S I C S Chapter 7: Waves and Vibrations Section 7C: Wave Properties and Sound

Mechanical Wave A disturbance that travels through a medium i.e. Sound requires medium of air or water

What is a Wave?

Mechanical Wave Waves transfer energy and not matter

Sine Wave Wave motion can be mathematically described by a sine or cosine wave

Two Types of Waves Transverse – disturbance is perpendicular to motion Longitudinal – disturbance is parallel to motion

Slinky Demonstration Energy is transported not matter Transverse vs. Longitudinal

Parts of a Wave Wavelength (λ) – distance in one cycle Amplitude – displacement Crest – high point Trough – low point Note: λ  Lambda

Sound Waves and Tuning Fork Demonstration Frequency  Pitch Amplitude  Volume Note: Frequency is wave cycles per second (Hz) 512 Hz 1024 Hz 2048 Hz

Speed of Sound Note: Sound travels faster in solids, liquids and gas respectively TempSpeed -10 o C325 m/s 0 o C331 m/s 10 o C337 m/s 20 o C343 m/s 30 o C349 m/s MediumSpeed Air (20 o C)343 m/s Helium972 m/s Alcohol1,143 m/s Water1,493 m/s Iron5,130 m/s Pyrex Glass5,640 m/s Diamond12,000 m/s

Wave Speed Equation

Frequency Equation

In-Class Problem #1 Determine the (a) number of waves, (b) wavelength, (c) amplitude, (d) frequency, (e) period and (f) wave speed.

In-Class Problem #1 Determine the (a) number of waves, (b) wavelength, (c) amplitude, (d) frequency, (e) period and (f) wave speed. waves = 2 λ = 0.04 m A = 0.02 m f = 0.4 Hz T = 2.5 s v = 0.016 m/s

In-Class Problem #2 A toy boat in the ocean rises every 3.0 s as wave crests pass by. The distance between wave crests is 5.0 m. Determine the (a) frequency, (b) period, (c) the wave length and (d) how fast are the waves traveling.

In-Class Problem #2 A toy boat in the ocean rises every 3.0 s as wave crests pass by. The distance between wave crests is 5.0 m. Determine the (a) frequency, (b) period, (c) the wave length and (d) how fast are the waves traveling. f = 0.33 Hz λ = 5.0 m T = 3.0 s v = 1.65 m/s

Assignment Problem Set 7C 7C-7D Quiz (Wave Properties and Behavior)

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