# Physics Ch 19 Waves Pg 362 Pendulum – simple harmonic motion period = time for 1 complete swing, T ** equation bottom of Pg 362 ** period only changed.

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Physics Ch 19 Waves Pg 362 Pendulum – simple harmonic motion period = time for 1 complete swing, T ** equation bottom of Pg 362 ** period only changed by length of pendulum – not mass!!

Springs – stretch and bounce back, simple harmonic motion force of bounce F = stiffness of spring k x distance of bounce x F = kx Hooke’s Law, bottom of Pg 363 k is a constant unique to each material like density, boiling point, etc. cheap vs expensive shock absorbers=diff k

Parts of Wave Pg 364 Frequency = vibrations per second, Hz AM – kHz, low f, long wave, low qual FM – MHz Radar – GHz Radio Pg 393 Pg 378 #25, 27

Types of Waves 1. Transverse – light, water, ropes energy moves up and down, wave moves forward, medium does not move!! Pg 365-7 ex. leaf on surface of water 2. Longitudinal – sound, compression wave, energy pushed forward through medium Speed = wavelength x frequency Pg 366

Interference Pg 369 1.Constructive – waves cresting together & combining, pumping self on a swing, bridge collapsing, tuning to radio station, rocking the pool, Pg 390 and 392 2.Destructive – waves cresting at diff times & cancelling (noise cancelling headphones Pg 391) Can create Standing Wave called resonance – appears to be still Pg 371 **good definition Pg 376**

Examples of Resonance Pumping yourself on a swing Bridge collapsing Tuning to a radio station Rocking the pool Microwave heating water in food Tones of wine glass, kettle drum Strings on violin, piano, guitar

Doppler and Bow Waves Pg 372 If source is moving forward – high pitch, waves pushed together, w/ light - blue shift As leaving – low pitch, waves spread out, w/ light - red shift – gives star info If source moving much faster than waves, creates a steep V shaped Bow Wave Pg 374 (wake of a boat, sonic boom, low pressure drag behind trucks)

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