MadSci Network: Physics |
Hi J Clark,
Why do snapping fingers make a noise? Well, first we have to think about what part of the finger
snapping motion causes the sound. Your students might be interested in doing an experiment
to
observe that it is in fact the impact of your finger on your palm that causes the "snap". The next
question, which you alluded to in your message, is how (and why) we hear this impact. Why do
claps
make a sound, for that matter? I suspect that this is an oversimplification, but one way of
explaining
it is that when your palms (or finger and palm) come together quickly, the air between them has
to
get away in a hurry. This causes a pressure wave –where air molecules get scrunched together–
that
travels outward from the source. Sound is a pressure wave so when it reaches our ears we hear a
"snap".
Cheers,
Tetjana
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