1 / 32

Waves

Waves. Physical Science Chapter 15. Waves. Rhythmic disturbances that carry energy through matter or space. Medium. What a wave travels through Solid Liquid Gas Mechanical waves – require a medium. Electromagnetic waves. Do not need a medium to travel through. As a wave travels.

samantha-horton
Download Presentation

Waves

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Waves Physical Science Chapter 15

  2. Waves • Rhythmic disturbances that carry energy through matter or space.

  3. Medium • What a wave travels through • Solid • Liquid • Gas • Mechanical waves – require a medium

  4. Electromagnetic waves • Do not need a medium to travel through

  5. As a wave travels • Each wave front gets bigger • Like the ripples from dropping a rock in a lake • Each wave front carries the same amount of energy • The energy is spread out over a larger area as the wave gets farther from its source

  6. Source of waves • Usually a vibration • Like vocal cords or speakers

  7. Simple Harmonic Motion • A type of vibration where energy changes form between kinetic and potential, but total energy is conserved. • A mass on a spring • A clock pendulum

  8. Discuss Why can supernova explosions in space be seen but not heard on Earth?

  9. Transverse wave • The medium moves at right angles to the direction the wave travels. • Crests – the highest points • Troughs – the lowest points

  10. Transverse wave • http://www.acoustics.salford.ac.uk/feschools/waves/wavetypes.htm#trans

  11. Longitudinal waves • The matter vibrates in the same direction as the wave is traveling. • Also called compressional waves.

  12. Longitudinal waves • http://www.acoustics.salford.ac.uk/feschools/waves/wavetypes2.htm

  13. Parts of a longitudinal wave • Compression – the area where the coils are packed together • Rarefaction – the area where the coils are spread apart.

  14. Surface waves Occur at a boundary between two different mediums, like water and air. Particles move both perpendicularly and parallel to the direction of wave travel. The particles make an elliptical or circular shape.

  15. Wavelength • The distance between a point on one wave and the identical point on the next wave. • Crest-to-crest • Trough-to-trough

  16. Wave Front • Leading edge of a wave • Shows the crests of the wave

  17. Amplitude • The distance from the crest (or trough) to the middle of the wave (called the rest position). • Waves with large amplitudes carry large amounts of energy. • Waves with small amplitudes carry small amounts of energy.

  18. Frequency • The number of wave crests that pass one place each second. • Expressed in hertz (Hz). • 1 Hz means one wave per second

  19. Period The amount of time needed for one complete cycle The reciprocal of frequency For waves – the amount of time between adjacent wave fronts

  20. Wave speed • How fast a wave moves. • To get speed, multiply frequency by wavelength.

  21. Wave speed Wave speed is measured in m/s Wave speed = frequency × wavelength

  22. Wavelength and frequency

  23. Practice • A wave is generated in a wave pool at a water park. The wavelength is 3.2 m. The frequency is 0.60 Hz. What is the velocity of the wave?

  24. Practice • A wave moving along a rope has a wavelength of 1.2 m and a frequency of 4.5 Hz. How fast is the wave traveling along the rope?

  25. Practice • Earthquakes can produce a transverse wave that travels at 5000 m/s. Its wavelength is about 417 m. What is its frequency?

  26. Practice • A tuning fork produces a sound wave with a wavelength of 0.20 m and a velocity of 25.6 m/s. What is the frequency of the tuning fork?

  27. Practice • A tuning fork produces a sound wave with a frequency of 122 Hz and a velocity of 343 m/s. What is the wavelength of the wave?

  28. Practice • A tuning fork produces a sound wave with a frequency of 252 Hz and a velocity of 343 m/s. What is the wavelength of the wave?

  29. Sound waves • Compressional waves. • Need a medium to travel through. • Travel faster through media where the particles are closer together. • Travel faster when the temperature is higher.

  30. Speed of sound in air • About 340 m/s at 20°C • Much slower than the speed of light • 300 000 000 m/s

  31. Doppler effect • When the source of sound is moving towards you, it sounds higher because the sound waves are compressed in front of it. • When the source is moving away, it sounds lower because the waves are pulled farther apart. • Also works if the source is still but the observer is moving.

  32. Discuss • Describe the changes in pitch that would occur as a police car with its sirens on passes you in pursuit of another car.

More Related