A bat flying in a cave emits a sound and receives its echo 0.1s later.
 How far away is the cave wall?

Hi daisy001:

The short answer to your question is - about 50 feet (15 meters) away. 

How is that calculated? Well, bats emit sonar - or sound waves - to
locate objects in their environment. The speed of sound is fairly
constant at about 1000 ft/s (or 300 m/s).

If the bat hears the sound after 0.1 seconds, then the sound must have
travelled for 0.05 seconds from the bat to the wall and another 0.05
seconds from the wall back to the bat's ears.

So, you need to figure out how far sound travels in 0.05 seconds. A
good formula for this would be:

Distance = Speed * Time
Distance = 1000 ft/s * .05s
Distance = 50 ft

Of course, if the bat is flying directly towards or away from the wall
when it sends the sound, then the result would be slighty altered -
but not significantly.

I hope this helps. 

websearcher

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Clarification of Answer by websearcher-ga on 27 Feb 2005 19:43 PST

A good page to look to for more information is:

Jim's Bat Page
http://www.jimlev.warc.org.uk/bats.htm

My search strategy for this (using Google):
* bat sonar "speed of sound"

websearcher

17,0145 m

I'm not sure where you found your speed of sound.  However the speed
of sound is taken to be the square root of specific heat ratio times
gas constant times temperature.

So that is 343 m/s.  If you don't believe me you can also check out:

speed of sound

in the google search and it will return ~340 m/s.
Your distance to the wall will then be 343*.1/2 = 17.15 m.
I think there was some confusion perhaps because the speed of sound in
water is usually around 1000 m/s.