Question

The temperature of the air is 20.0 degrees Celsius when a tourist drops a coin into a wishing well. She hears the splash 5.30 s after drops the coin. If air resistance is ignored, how deep is the well?

Answer 1

time to fall:
h = .5 g t^2
so t = sqrt (2 g h)

time for sound to rise = h/c

5.3 = h/c + sqrt (2 g h)

sqrt (2 g h) = 5.3 - h/c

2 g h = 5.3^3 - 10.6 (h/c) + h^2/c^2

look up c at 20 deg C
and then solve the quadratic

Answer 2

120

Answer 3

100