Physics

The temperature of the air is 20 Celsius when a tourist drops a coin into a wishing well. She hears the splash 5.30s after she drops the coin. If the air resistance is ignored, how deep is the well?
a) 344m b)332m c)137m d)120m e)0.60m

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  1. time it takes the coin to fall: h=1/2 g t^2
    t=sqrt(2h/g)
    time it takes sound to come back: h/vs

    given: those times add to 5.2 seconds

    5.2=sqrt(2H/g)+h/v
    a quadratic: let u=sqrt h so u^2=h
    u^2/v+u(sqrt2/g)-5.2=0
    u^2+u*vsqrt(2/g)-5.2v=0
    calculate v for that temerature, then use the quadratic equation to solve for u (and square it for h)

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    bobpursley
  2. i dont really understand the explanation, so which would be the answer

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