Question

On a day that is 30°c, you drop a rock from the top of a well. You hear the sound of the rock hitting the bottom 0.6s after you drop it. How deep is the well?

Answer 1

find v, the speed of sound. If the depth of the well is y, then the time taken for the sound to come back is y/v

Using the equation of motion, we have
4.9t^2 = y
Thus, the time it takes to hit the water is √(y/4.9)

Adding up the times, we have

√(y/4.9) + y/v = 0.6

Plugging in your value for v, you just need to solve that for y.