110 likes | 235 Views
Properties of Waves and Sound. Barton Spring 2014 Honors Physics. Difference between wave motion and particle motion :. Both carry energy Particles move and carry energy through a transfer of matter A wave is a disturbance that carries energy through matter or space.
E N D
Properties of Waves and Sound Barton Spring 2014 Honors Physics
Difference between wave motion and particle motion: • Both carry energy • Particles move and carry energy through a transfer of matter • A wave is a disturbance that carries energy through matter or space
Mechanical waves: (like sound) • Require a medium through which to travel • ie: water, air, ropes, spring • CANNOT travel in a vacuum • Pulse – single wave
Mechanical waves: • Longitudinal wave- vibrates parallel to direction of wave’s motion • Sound waves • Transverse wave - vibrates perpendicular to direction of wave’s motion http://nanobioart.com/members/ageorge/
Mechanical waves: • Surface waves – characteristics of both transverse and longitudinal waves; particles move parallel and perpendicular to direction of wave motion Equilibrium position (rest position)
Wave behavior: • Speed of wave depends only on the medium it passes through (not amplitude or frequency) • Incident wave – wave that strikes a boundary • Reflected wave – returning wave that has bounced back from a boundary • faster wave speed slower wave speed --- reflected wave is inverted • slower wave speed faster wave speed --- reflected wave is not inverted • http://paws.kettering.edu/~drussell/Demos/reflect/reflect.html <---- demos of waves on rope
Wave behavior: • Principle of Superposition – displacement of a medium caused by 2 or more waves is the sum of the displacements caused by individual waves • Interference – result of superposition of 2 or more waves • http://paws.kettering.edu/~drussell/Demos/superposition/superposition.html<---superposition videos CONSTRUCTIVE DESTRUCTIVE http://www.circleofoneness.org/ether.html
Wave behavior: • Refraction – change in direction of waves at the boundary between two different mediums, bending of the wave http://www.crd.bc.ca/watersheds/protection/geology-processes/Waves.htm
Perceiving sound: • Pitch – depends on frequency • Loudness – depends on amplitude • Sound level – measuring scale of amplitudes • Decibel (dB) – unit for measurement of sound level • Medium determines wave speed http://raider.mountunion.edu/~miskeljp/ds/schedule.htm0
Doppler effect: • Doppler effect – frequency shift due to sound source movement • Closer/towards higher frequency • Further/away lower frequency • Equation: • Song: http://imagine.gsfc.nasa.gov/YBA/M31-velocity/Doppler-shift-3.html Think about it: If the source and observer are moving towards each other, the waves get bunched together and the frequency goes up. If the source and observer are moving further apart, the frequency will decrease as the waves get stretched apart. Keep this in mind as you apply the equation!