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Vibration and Waves

Vibration and Waves. Vibrations. What is it? A vibration is an oscillation A back and forward motion that repeats How does a bell work? . Wave. What is a wave? Give an example Waves are disturbances in time an space without the transfer of matter Sound waves, light waves, water waves.

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Vibration and Waves

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  1. Vibration and Waves

  2. Vibrations • What is it? • A vibration is an oscillation • A back and forward motion that repeats • How does a bell work?

  3. Wave • What is a wave? Give an example • Waves are disturbances in time an space without the transfer of matter • Sound waves, light waves, water waves

  4. Wave of a Pendulum T = 2π√(L ∕g) • Does the mass of the pendulum effect the time it takes for it to swing back and forth. • Period is the time is takes for a pendulum to swing back and forth, or to complete a full cycle

  5. Simple Harmonic Motion • Periodic motion where acceleration is proportional to the equilibrium position and is directed towards that position.

  6. Label each part

  7. Wave Motion • When you drop a stone in a pond, what happens? • Is the water moving? • What about a string that vibrates?

  8. Wave speed • v = λf • v – is wave speed Units: m/s • λ - wavelength m • f- is the frequency Hz or 1/s • Wave speed depends on the medium that it travels through.

  9. Transverse and Longitudinal waves

  10. Interference Constructive Destructive

  11. Standing Waves

  12. The Doppler Effect • What happens if a bug remains stationary and jumps up and down on the waters surface.

  13. Why does a siren sound different when it changes positions. • Put yourself as a the stationary position, and you witness the vehicle with the siren, describe the noises • Draw it on your notebook

  14. If the object moves slower than the wavespeed

  15. Sound Waves

  16. Origin • Sound is produced from the vibrations of materials • All sound waves are longitudinal waves • Pitch: is the frequency of sound • Higher pitched sounds have high frequencies • Lower pitched sounds have lower frequencies

  17. Ultrasonic and infrasonic • Ultrasonic waves are sound waves that have a frequency above 20,000 Hz • Infrasonic waves are sound waves that have a frequency lower than 20 Hz • We as humans can not hear either of these waves since our hearing range is between the two ranges and it continues to shrink as we get older.

  18. Sounds and Media • Sound waves travel best through which media? • A) Gases • B) Solids • C) Liquids • What about a vacuum?

  19. Speed of sound and Loudness • In dry air, the speed of sound is 330 m/s at 0°C • As the air get more humid the speed increases, why? • As the temperature increases, the speed increases, why? • Loudness is determined by the intensity of the sound which in turn is the square of the amplitude

  20. Natural Frequency and Resonance • Natural Frequency:A frequency at which an elastic object once energized will vibrate. • Essentially it is the vibration that occurs in every substance when it is disturbed. • Ex dropping a wrench and a baseball bat at the same time, do they sound the same? • This is opposite to Forced vibrations, which are disturbances caused by unnatural sources • Hitting a guitar string

  21. Resonance • This is when the natural frequency and the frequency of the forced vibration match. • What occurs is the amplitude of the sound waves increase dramatically. This bridge collapased and injured 40 of the 3000 men were injured.

  22. Beats • Two tones of slightly different frequencies are sounded together. • You get both constructive and destructive interferences • This is what we call a variation of loudness

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