Types of Waves: Transverse and Longitudinal
Mechanical Waves are waves which propagate through a material medium (solid, liquid, or gas) at a wave speed which depends on the elastic and inertial properties of that medium. There are two basic types of wave motion for mechanical waves: longitudinal waves and transverse waves
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ð The particle displacement is perpendicular to the direction of wave propagation.
ð The particles do not move along with the wave; they simply oscillate up and down about their individual equilibrium positions as the wave passes by.
ð A ripple on a pond and a wave on a string are easily visualized transverse waves. |
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Longitudinal Waves ð The particle displacement is parallel to the direction of wave propagation. ð The wave is seen as the motion of the compressed region (ie, it is a pressure wave), which moves from left to right. ð A "slinkey" is a good example of a longitudinal wave. Another is the propagation of sound waves in air. |
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Transverse and Longitudinal Waves - Earthquakes
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Transverse S waves depends on the shear strength of the material. Imagine a very long and narrow block of Jello, and then imagine shaking the end of it and then imagine shaking the end of it from side to side. A shear wave will propagate down the long length of it. You shake it from side to side but the wave travels forward and perpendicular to the direction of shaking. You can try this with a long spring or a Slinky suspended from strings also. If you give it a sudden sideways deflection and a transverse or shear wave will travel both lengths of the spring. Now try to imagine doing the same thing with water in a tank. No shear wave will propagate because gases and fluids have no shear strength. They give too easily. However, the strength of atomic bonds in solids allows them to transmit tranverse motions. |
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Longitudinal P waves (or "longitudinal waves") travel through fluids, and solids. They are compression waves and rely on the compressional strength and elasticity of the materials to propagate. They are known as body waves because they travel though the body of a material in all directions and not just at the surface, as water waves do. For P waves, the motion of the meterial particles that transmit the energy move parallel to the direction of propagation. P waves travel the same way as sound waves in air. |
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