A boy claps in front of a wall and hears the echo 0.35 s later.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A boy claps in front of a wall and hears the echo later. How far is the wall? (Speed of sound )
Need a reminder? The key ideaShow
An echo travels to the reflector and back: . A separate echo needs at least (a wall at least away in air). SONAR uses ultrasound in sea water, about .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The whole path is .
Step 2. Half of it: .
Answer: .
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