Saturday, February 4, 2012

Resonance problem. Can anyone help?

A lady is observing the fireworks from the Baltimore Inner Harbor at a distance twice that of a man. How many times more intense is the sound for the man than for the woman?Resonance problem. Can anyone help?
This is not a resonance problem. This is a sound propagation problem.



The power drops with the square of distance, simply because in general sound waves from a point source propagate in every direction. The surface of the propagating wavefront is that of a sphere, and it grows as a square of the radius.



Thus the sound is 2^2 = 4 times more intense for the man.



A firework is a good approximation of a point source, when listened to from a reasonable distance: it's a "small" explosive charge.Resonance problem. Can anyone help?
I'm guessing 4?



It would depend on whether the firework was to be considered a point source or not.



If so, then it would follow an inverse square law, in which a double in distance would result in a decrease by 4 :)

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