Speaker 1: Welcome to brain Stuff from how stuff works dot com
Speaker 1: where smart Happens. Hi Am Marshall Brain with today's question,
Speaker 1: what causes a sonic boom from an airplane? You can
Speaker 1: learn a lot about sonic booms by looking at the
Speaker 1: wakes that boats leave in the water. If you toss
Speaker 1: a pebble into a pond, little waves will form in
Speaker 1: concentric circles and propagate away from the point of impact.
Speaker 1: If a boat travels through the pond at three to
Speaker 1: five miles per hour, little waves will propagate in the
Speaker 1: same way, both ahead of and behind the boat, and
Speaker 1: the boat will travel through those little waves. If a
Speaker 1: boat travels faster than the waves can propagate through the water,
Speaker 1: then the waves can't get out of the way of
Speaker 1: the boat fast enough and they form awake. Awake is
Speaker 1: a large single wave. It's formed out of all the
Speaker 1: little waves would have propagated ahead of the boat but can't.
Speaker 1: When an airplane travels through the air, it produces sound waves.
Speaker 1: If the plane is traveling slower than the speed of sound,
Speaker 1: which is something like seven miles per hour, then sound
Speaker 1: waves can propagate ahead of the plane. If the plane
Speaker 1: breaks the sound barrier and flies faster than the speed
Speaker 1: of sound. It produces a sonic boom when it flies past.
Speaker 1: The boom is the wake of the plane sound waves.
Speaker 1: All of the sound waves that would have normally propagated
Speaker 1: ahead of the plane are combined together, so at first
Speaker 1: you hear nothing, and then you hear the boom that
Speaker 1: those sound waves create together. It's just like being on
Speaker 1: the shore of a smooth lake when a boat speeds passed.
Speaker 1: There's no disturbance in the water as the boat comes by,
Speaker 1: but eventually a large wave from the wake rolls onto shore.
Speaker 1: When a plane flies passed its supersonic speeds, the exact
Speaker 1: same thing happens, but instead of a large wake wave
Speaker 1: from a boat, you get a sonic boom of sound
Speaker 1: waves from an airplane. Be sure to check out our
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