Understanding Wave Motion: Interference, Propagation, and Oscillation Principles
This lecture discusses the fundamental concepts of wave motion, including mechanical waves, oscillations, and resonance. It explores the differences between transverse and longitudinal waves, wave properties such as period and wavelength, and the effects of superposition and standing waves. Pre-lecture questions engage students on simple harmonic motion, resonance, and the characteristics of waves. Interactive simulations are referenced to illustrate key principles such as wave propagation and interference. This comprehensive overview aids students in grasping the intricacies of wave dynamics in physics.
Understanding Wave Motion: Interference, Propagation, and Oscillation Principles
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Presentation Transcript
PHYS16 – Lecture 37 Ch. 16 Wave Motion “Interference is much clearer in HD”
Oscillations pre-question • Is a bouncing ball an example of simple harmonic motion? • Yes • No
Oscillations pre-question • Two kids are swinging on two swings of the same height – one kid is a little chubbier than the other. Neglecting frictional forces, which kid completes a back and forth swing in the fastest time? A) The chubby kid B) The skinny kid C) The kid who pushes off the ground the best D) Both complete in the same time
Oscillations pre-question • A mass on a spring is driven at a driving frequency (red curve) and the resulting position vs. time of the mass is given (blue curve). Which case is closest to resonance?
Ch. 16 Wave Motion • Mechanical Waves • Transverse vs. Longitudinal • Properties • Example: Wave on a String • How the wave propagates • Speed • Reflection and Transmission • Superposition and Standing Waves
Waves pre-question PhET website
Waves pre-question 0.0133 PhET website
Mechanical Waves • A propagating oscillation that moves through a medium Transverse – water waves, disturbance on a string Longitudinal – sound waves, slinky or spring
Mechanical Waves • Waves use at least 1-3 space dimensions and time… • Ex. – Water waves propagate in x, move “up and down” in y, and change position with time • Ex. – Sound waves propagate in x, move “up and down” in x, and change position with time
Wave Properties • Period – high period medium period low period T
Wave Properties • Period – • Wavelength and Wave number – http://seagrant.uaf.edu/marine-ed/curriculum/images/stories/grade7/wave.jpg
Wave Properties • Period – • Wavelength and Wave number – http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/Images_specific/wave_def.gif
Wave Properties • Period – • Wavelength and Wave number – • Wave speed – http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/Images_specific/wave_def.gif
Example: Speaker Speed = Period = Wave number = Wavelength = 330 m/s 0.0038 s 5.0m-1 1.25 m PhET website
Example: Sand on a vibrating plate • Sand is placed on the vibrating plate below. Which apparatus is vibrating the plate with the highest wave number?
Wave Function or Waveform Plane Wave Higher Dimension Wave
Wave on a String • You can generate a wave on a string by pulsing sting with your hand • Speed of pulse/wave is related to tension in string and mass density of string PhET website
Propagation of Pulse • If you advance the movie one frame point A will move… (higher, lower, right, left)? • If generate new pulse but more quickly than first then it will be… (same, wider, narrower)? • If generate new pulse but move hand higher than first then it will be… (same, taller, shorter)? • If generate new pulse with rope tightened then pulse will be… (same, faster, slower)? PhET website
Wave on String Simulation PhET website
Example Question PhET website
Main Points – Wave Properties • Mechanical Wave – a propagating oscillation that moves through a medium • Period – • Wavelength and Wave number – • Wave speed –