Everything Science Grade 11

14.5 CHAPTER 14. LONGITUDINAL WAVES

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Figure 14.5: Graph of particle displacement asa function of time for the longitudinal wave shown in
Figure 14.4.

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Figure 14.6: Graph of velocity as a function of time.

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Figure 14.7: Graph of acceleration as a functionof time.

Sound waves travel faster through liquids, like water, than through the air because water is denser
than air (the particles are closer together). Sound waves travel faster in solids than in liquids.

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compressions

rarefactions

tuning

fork

column of air in front

of tuning fork

Figure 14.8: Sound waves are pressure waves and need a medium through which to travel.

A sound wave is a pressure wave. This means that regions of high pressure (compressions) and low
pressure (rarefactions) are created as the soundsource vibrates. These compressions and rarefactions
arise because the sourcevibrates longitudinally and the longitudinal motion of air produces pressure
fluctuations.

Sound will be studied inmore detail in Chapter 15.