something from physics class

physicsgurl2007 · #1 May 10, 2007, 09:10 AM

Carol drops a stone into a mine shaft 122.5m deep.How soon after she drops the stone does she hear it hit the bottomof the shaft?

asterisk_man · May 10, 2007, 09:46 AM

use $y= y_0 + v_0 t - \frac {a t^2} {2}<br />$
solve for t with y=-122.5 and put in the correct values for y0 v0 and a

ebaines · May 10, 2007, 09:46 AM

Quote:

Originally Posted by physicsgurl2007

Carol drops a stone into a mine shaft 122.5m deep.How soon after she drops the stone does she hear it hit the bottomof the shaft?

Two parts to this problem: first you have to determine (a) how long it takes for the stone to fall 122.5m, then (b) how long it takes for sound to travel back up the shadt 122.5m. Add them together. So, do you know how to do parts (a) and (b)?

asterisk_man · May 10, 2007, 10:35 AM

oh, i was in too much of a rush to remember to explain part (b). nice catch ebaines. that'll teach me to be distracted!



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