Physics Ch 19 Waves Pg 362 Pendulum simple

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 – k. Hz, 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)