SMDEP Physics Waves: Standing Waves, Sound Waves Webpage updated:

Harmonic Motion and Waves in the Real World: Harmonic Motion: springs (car shocks, slinkys, DNA molecules) –Pendulums (clocks, swings, skyscrapers) –Periodic motion: orbiting satellites, planets, stars, galaxies Waves: Sound –Sonar (bats, submarines) –Ultrasound (reflection/transmission of waves depends on density) Waves: Light (Electromagnetic waves) –X-rays (see Ultrasound) –Lasers (pointers, grocery stores, cat toys, space weapons) –Radio (AM/FM, satellite), TV (broadcast) –Microwave (microwave ovens, cordless phones, cell phones) Waves: Compressional (density waves) –Traffic slowdowns –Spiral galaxies –Sound

Ch 16, #3: distance 1.5 m m 3.50 m m 5.Other 6.Didn’t finish

Ch 16, # dB 2.97 dB 3.80 dB 4.87 dB 5.Other 6.Didn’t finish

Ch 16, #61: horn frequency? Hz Hz Hz 4.66 Hz 5.Other 6.Didn’t finish

Ch 16, #63: beat frequency? 1.45 Hz 2.91 Hz Hz Hz 5.Other 6.Didn’t finish

What is required to produce a standing wave? 1.Two oppositely traveling waves 2.Same frequency 3.Same wavelength 4.Same amplitude 5.All of the above

Consider the sum of two similar waves (same amplitude, wavelength, frequency) traveling in opposite directions. What is the amplitude of the standing wave they produce? 1.Same as either wave 2.Twice the amplitude of either wave 3.Half the amplitude of either wave 4.Zero 5.None of the above

Consider the sum of two similar waves (same amplitude, wavelength, frequency) traveling in opposite directions. What is the wavelength of the standing wave they produce? 1.Same as original wavelength 2.Twice the original wavelength 3.Half the original wavelength 4.Cannot tell without knowing the phase difference

Consider the sum of two similar waves (same amplitude, wavelength, frequency) traveling in opposite directions. What is the frequency of the standing wave they produce? 1.Same as original frequency 2.Different from the original frequency

Two sound waves combine to form beats, which occur 3 times a second. Two different sound waves combine to form a different set of beats, which occur 2 times a second. For which pair of waves is the frequency difference greater? 1.The first pair (3 beats a second) 2.The second pair (2 beats a second) 3.Same for both 4.Need more info

Doppler shift source moves toward detector  shorter (higher f) source moves away from detector  longer (higher f)

detector moves away from source  longer (higher f) detector moves toward source  shorter (higher f) Doppler shift

Doppler shift formula f’ = f (v  v D ) _____ (v  v S )

Two sound waves travel in the same region and thus interfere with each other. What is required to produce 100% destructive interference? 10 0 of 70 1.Waves have same frequency 2.Waves have same amplitude 3.Waves differ in phase by  radians 4.All of the above 5.None of the above

Joe hears a fire engine siren coming towards him at speed v. For Jane to hear the identical pitch (frequency) from the siren of a stationary fire engine, she would have to: 10 0 of 70 1.Be standing still 2.Be moving towards the fire engine at speed v 3.Be moving towards the fire engine at some other speed 4.Be moving away from the fire engine at speed v 5.Need more info

A submerged submarine sends a sonar wave into the surrounding ocean, and it (the wave) reflects off a distant object. If the sub is moving away from the object that reflects the sonar wave, the frequency of the reflected wave is 10 0 of 70 1.Smaller than 2.Equal to 3.Larger than 4.(depends on motion of distant object) 5.(need more info) … the frequency of the emitted wave