When you crack a knuckle, you suddenly widen the knuckle cavity, allowing more volume
Chapter 17, Problem 31(choose chapter or problem)
When you crack a knuckle, you suddenly widen the knuckle cavity, allowing more volume for the synovial fluid inside it and causing a gas bubble suddenly to appear in the fluid.The sudden production of the bubble, called cavitation, produces a sound pulsethe cracking sound. Assume that the sound is transmitted uniformly in all directions and that it fully passes from the knuckle interior to the outside. If the pulse has a sound level of 62 dB at your ear, estimate the rate at which energy is produced by the cavitation.
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