Have You Heard About The Speed of Sound?

The speed of sound can be hard to grasp for some.  After all, there are other speeds that we are more comfortable with that we use daily.  Just about anyone can judge what rate of speed is in miles per hour, or kilometers per hour.  We see those measurements all of the time driving down the road.  Up until the last century, it was difficult for anyone to imagine travelling at the speed of sound, and most probably didn't understand just what that speed is.

Let's look at sound.  Sound is a vibration that travels through a medium.  For what we hear, it is a vibration through the air.  Air is the medium.  If you are under water, vibrations travel through the liquid and the water is the medium.  The density of the medium has a large affect on how fast sound can travel through it.  The more dense it is, the faster the sound will travel.  Water is thicker than air and therefore a sound travelling through water will move faster than through the air.

When we are measuring the speed of a vehicle, like an airplane, we are normally looking at the speed of sound through air.  When a jet plane creates a sonic boom, it has reached a speed greater than the speed of sound.  As mentioned before, the density of the air will determine at what speed the jet will need to travel to break the sound barrier.  Temperature can have a large affect on the density of the air.  Hot air is going to be less dense than cold air.  Air close to sea level is going to be more dense than air at higher altitudes.  So the speed of sound on a hot day at high altitude will be slower than the speed of sound at low altitude on a cold day.  The standard used for the speed of sound is the speed in dry air at 68 degrees Fahrenheit.  This speed is 768 mile per hour.

To see how much affect the air temperature has on the speed of sound try looking at these calculators.
Speed of Sound Calculator (Fahrenheit)
Speed of Sound Calculator (Celsius)

Now that you have a better understanding of the speed of sound, you can look at other aspects of your life an understand why you may see something and hear it a moment later.  For example, you may be at a football game and see the kicker kick the ball in the distance, but hear it a moment later.  You can also see lightning and hear the thunder after a few moments.  Using the speed of sound you can count how many seconds there is between seeing the lightning, and hearing the thunder to estimate the distance you are from the lightning strike.

Lightning Strike Distance Calculator

In the meantime, try to keep your daily commute at a safe speed and don't try to break any sound barriers on your daily commute.

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