oscillations waves Doppler, Shock wave And S.R. lab Sound and Music 100 100 100 100 100 200 200 200 200 200 300 300 300 300 300 Notes notes notes 400 400 400 400 400 500 500 500 500 500

Oscillations 100 What is the frequency of an oscillation that has a period of 4 seconds?

Oscillations - 200 If you double the frequency of a vibrating object, what happens to its period?

T = 1/f So frequency halves

Oscillations - 300 A mass oscillates on the end of a spring. You increase the amount of mass hanging on a spring. What happens to the period of oscillation?

The period increases

A pendulum oscillates with the following attributes: Oscillations – 400 A pendulum oscillates with the following attributes: What is the amplitude of the pendulum’s oscillation? 45 cm 25 cm

Lowest to highest vertical displacement: 25 cm

Oscillations - 500 What is the period of the minute hand of the classroom clock? (give your answer in SI units)

The minute hand rotates all the way around the dial every 60 minutes 60 minutes*60 seconds/minute = 3600 s

Waves - 100 The amplitude of a wave in water is 1 meter. What is the top-to-bottom distance of the disturbance (the peak-to-trough distance)?

2 m

Waves - 200 What is the difference between longitudinal and transverse waves? What kind of wave is a sound wave?

Longitudinal – wave medium vibrates parallel to wave velocity Transverse – wave medium vibrates perpendicular to wave velocity Sound is a longitudinal wave

Waves - 300 A sailor is watching waves pass his anchored boat. Two wave crests pass every 3 seconds. What is the frequency of the waves?

1/3 Hz

Waves - 400 What is the wavelength of a 512 Hz sound wave, which travels through the air at a speed of 340 m/s?

Waves– 500 A certain ocean wave has a frequency of 0.05 Hz and a wavelength of 10 meters. What is the wave’s speed?

When a sound source moves towards you, what happens to the wave speed? Doppler Effect - 100 When a sound source moves towards you, what happens to the wave speed?

Nada! Wave speed stays the same (it would only change if the air itself changed)

Doppler Effect - 200 If you were in a very fast car, shining a yellow flashlight at your friend, but driving away from your friend, what color light would she see?

Your friend would see the light “red-shifted” Instead of yellow light, she would see orange or red (depending on how fast you were going, compared to the speed of light)

Doppler Effect - 300 Your friend is standing still, singing a “middle C” (256 Hz). You run toward your friend. What new note are you most likely to hear: The same note (a 256 Hz C) A higher-pitched note (say, a 288 Hz D) - A lower-pitched note (say, a 250 Hz B-sharp)

You would hear a higher pitched noted (you run into the wave crests he produces more frequently than if you were standing still)

Doppler Effect - 400 What happens when the source of a wave travels faster than the speed of the wave (explain and use correct terminology)?

(doesn’t work for light) Shock wave (doesn’t work for light)

Doppler Effect - 500 What happens to the shock wave following a supersonic jet as the jet flies faster and faster?

Conical shock wave becomes narrower

Labs - 100 Where can you touch a standing wave on a rope without disturbing the wave (and without getting hit by the jiggling rope)? Use the correct wave-terminology!

At a node

Labs – 200 You are shaking a slinky, making a transverse wave. What do you have to do to make the waves on the slinky travel faster?

Change the slinky: Pull it tighter Allow more slack Get a different slinky (made out of some other material)

What determines the note you play? Labs – 300 You are playing a note by banging on a piece of PVC pipe (like a member of the Blue Man Group) What determines the note you play?

The length of the pipe

Labs - 400 You and your friend both send a pulse down opposite sides of a slinky that is stretched across the classroom floor. What is the amplitude of the slinky oscillation at the moment in time when the two pulses meet at the middle of the slinky if your pulse has an amplitude of 0.5 m and your friend’s pulse has an amplitude of 0.3 m.

Since the pulses are on opposite sides of the slinky, their amplitudes subtract – the combined pulse has an amplitude of 0.2 m.

Labs - 500 You find that a 1-closed ended PVC pipe resonates at 440 Hz when it is 19.6 cm long. According to your measurement, what is the speed of sound in air?

345 m/s: Show work!

What produces sound waves? Sound and Music - 100 What produces sound waves?

Vibrating objects (vibrating drum heads, vibrating strings, vibrating speakers, vibrating tuning forks, etc)

Sound and Music - 200 Upon which of the following does the speed of sound depend? The frequency of the sound The wavelength of the sound The air temperature All of the above

Just air temperature – wave speed depends only on the characteristics of the medium through which it travels

What is the difference between resonance and forced vibration? Sound and Music - 300 What is the difference between resonance and forced vibration?

Forced vibration: one vibrating object causes another to vibrate by contact. Resonance: an object is forced to vibrate at its natural frequency

Sound and Music - 400 How do the strings of stringed instruments produce musical notes: be specific – what vibrates and how, how is the natural frequency of the vibrating object related to the sound you hear?

The note you play is the 1st harmonic (fundamental frequency) There are 2 nodes on the string; nodes are at the ends of the string

Sound and Music - 500 How do the pipes in an organ produce musical notes: be specific – what vibrates and how, how is the natural frequency of the vibrating object related to the sound you hear?

Wind instruments produce standing longitudinal waves Standing waves occur in the air inside the body of the instrument Resonant (fundamental) frequency depends on Length of the pipe/body of instrument Density of air in the instrument Both ends open Fundamental frequency occurs when the standing wave has one node (in the middle)