It used to be thought that the cracking noise of a [[whip]] was due to leather striking leather but, after using high speed [[photography]] to study the motion of the whip, it was discovered that the crack is actually the tip of the whip breaking the sound barrier. | It used to be thought that the cracking noise of a [[whip]] was due to leather striking leather but, after using high speed [[photography]] to study the motion of the whip, it was discovered that the crack is actually the tip of the whip breaking the sound barrier. |