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Waves

Waves. The Nature of Waves. What is in a wave?. A wave is a repeating disturbance or movement that transfers energy through matter or space. For example, during earthquakes, energy is transferred in powerful waves that travel through Earth. . Wave and Energy.

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Waves

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  1. Waves

  2. The Nature of Waves

  3. What is in a wave? • A wave is a repeating disturbance or movement that transfers energy through matter or space. • For example, during earthquakes, energy is transferred in powerful waves that travel through Earth.

  4. Wave and Energy • A pebble falls into a pool of water and ripples form. • Because it is moving, the falling pebble has energy.

  5. As it splashes into the pool, the pebble transfers some of its energy to nearby water molecules, causing them to move. • What you see is energy traveling in the form of a wave on the surface of the water. • Raft

  6. The waves don’t even carry the water along with them. • Only the energy carried by the waves moves forward. • All waves have this property • They carry energy without transporting matter from place to place.

  7. Making Waves • A wave will travel only as long as it has energy to carry. • Anything moving up and down or back and forth in rhythm is vibrating. • All waves are produced by vibrating matter

  8. Mechanical Waves • Some wave require matter to transfer the energy. • The matter the waves travel through is called a medium. • The medium can be a solid, a liquid, a gas, or a combination of these.

  9. The two types of mechanical waves are transverse waves and compressional waves.

  10. Transverse Wave • In a transverse wave, matter in the medium moves back and forth at right angles to the direction that the wave travels. • For example, a water wave travels horizontally as the water moves vertically up and down.

  11. Compressional Waves • In a compressional wave, matter in the medium moves back and forth along the same direction that the wave travels. • The wave carries energy, but not matter, forward along the spring.

  12. Compressional waves also are called longitudinal waves • Sound creates compressional waves.

  13. Deep Water Waves • A water wave causes water to move back and forth, as well as up and down. • This motion causes both transverse and compressional waves

  14. Seismic Waves • Forces in Earth’s crust can cause regions of the crust to shift, bend, or even break. • The breaking crust vibrates, creating seismic waves that carry energy outward.

  15. Seismic waves are a combination of compressional and transverse waves. • They can travel through Earth and along Earth’s surface.

  16. Wave Properties

  17. The Parts of a Wave • Transverse waves and compressional waves have different characteristics: crests and trough, compressions and rarefactions. • They also have similar properties: wavelength, frequency, period, amplitude, and wave speed.

  18. The Parts of a Transverse Wave • A transverse wave has alternating high points, crests, and low points, troughs. Rest position is also called equilibrium.

  19. Wavelength of Transverse Wave • A wavelength, , is the distance between one point on a wave and the nearest point just like it. • Wavelength is the distance from crest to crest or trough to trough.

  20. The Parts of a Compressional Wave • A compressional wave has regions where the particles are close together, compressions. • And regions where the particles are further apart, rarefactions.

  21. The wavelength of a Compressional Wave • A wavelength is the distance between two neighboring compressions or two neighboring rarefactions.

  22. Amplitude • Amplitude is related to the energy carried by a wave. • The greater the wave’s amplitude is, the more energy the wave carries.

  23. Amplitude of a Transverse Wave • The amplitude is the distance from the crest or trough of the wave to the rest position of the medium.

  24. The Amplitude of a Compressional Wave • The amplitude of a compressional wave is related to how tightly the medium is pushed together at the compressions. • The denser the medium is at the compressions, the larger its amplitude is and the more energy the wave carries.

  25. Frequency, f • The number of wavelengths that pass a fixed point each second. • The rate of vibration • Find the frequency of a transverse wave by counting the number of crests or troughs that pass by a point each second. • Expressed in Hertz (Hz).

  26. Period, T • The amount of time it takes one wavelength to pass a point. • As the frequency of a wave increases, the period decreases. • Units of seconds, s.

  27. Frequency & Period • The frequency, f, and period, T, are reciprocals of each other.

  28. Speed of a Wave • The speed of a wave depends on the medium it is traveling through. • Sound travels faster in solids than gases. • Light travels faster in air than water.

  29. Calculating the Speed of a Wave • v=fl • Where: • v is speed in m/s • f is frequency in Hz • l is wavelength in m

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