A mountaineer estimates the depth of a crevasse by dropping a stone and listening for sound when the stone hits the bottom. The speed of sound in air is 340m/s. If the sound is heard 10s after the stone is dropped, what is the depth of the crevasse?

Question

A mountaineer estimates the depth of a crevasse by dropping a stone and listening for sound when the stone hits the bottom. The speed of sound in air is 340m/s. If the sound is heard 10s after the stone is dropped, what is the depth of the crevasse?
Do you find velocity first? i could not find any equation where i would only have one unknown for this question. please help?

bobpursley · Answer

break up the journey in going down, sound coming up.
Let tf be the time of fall. Then 10-tf is the time of the sound going up. In both cases, the distance is the same.

df=1/2 g tf^2
ds=vs*(10-tf)
Now, set ds=df, and solve for tf.

Once that is determined, you can find df.

Simanga Gamedze · Answer

a stone is dropped into a well. The sound is heard 30s after the? stone is dropped. What is the depth of the well? Note that the speed of sound in air is 343m/s.