Water Level in a Well
Date: 10/09/2001 at 18:50:14 From: Jason Subject: Word Problem A man wishes to determine the water level in a deep well. He drops a stone into the well and hears the stone hit the water 3 seconds later. If the stone drops 16t^2 feet after t seconds, and the speed of sound is 1090 ft/s, how far below the opening of the well is the surface of the water (to the nearest foot)? I tried to apply physics to it.
Date: 10/10/2001 at 12:18:09 From: Doctor Ian Subject: Re: Word Problem Hi Jason, The time (t) required for the stone to hit the water is given by d = 16t^2 where d is the distance to the surface of the water. The time (T) required for the sound to come back is given by d = (1090)T which means that 16t^2 = (1090)T We're also told that the round trip time (t+T) is 3 seconds, so t + T = 3 Now you have two equations with two unknowns. Can you take it from here? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.