AK asked in Science & MathematicsPhysics · 2 months ago

# Physics question?

I need to do this for homework but i dont even know how to do this question:

A person situated in a valley, exactly in the middle two mountains, screams;

at 4.0s it echoes back to him

at 4.6s it echoes back to him a second time

Calculate the distance between the two mountains knowing the speed of sound is 340m/s.

What formula do I even use for this?

Relevance
• Vaman
Lv 7
2 months ago

Let him be in the middle. The distance be x to one mountain and x+h to the second mountain.  He will hear echo after 2x/v=4 time. The second time it will be 2 (x+h)/v=4.6. The distance between mountain will be 2x+h.

x+h=v*2.3, x=2*v, 2x+h= 4.3 v, Put the value of the sound velocity.

4.3*340=1462 m is the distance between mountains.

• Andrew Smith
Lv 7
2 months agoReport

If one is at distance x and the other at x+h how can he be in the EXACT MIDDLE?

• 2 months ago

If this is the exact wording of the question, There is no answer because there is no question. You cannot answer statements of facts. This is a puzzle. If he is situated exactly in the middle (given), How can the times be unequal? There may be a very heavy fog bank on one side or there may be a hotel on one side

.

• Andrew Smith
Lv 7
2 months agoReport

But that still does not explain how you got an echo at 4 s.  If EACH echo was at 0.6 then the sixth echo happened at 3.6 s and the seventh at 4.2s which disagrees with other facts.

• Anonymous
2 months ago

< facepalm >

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• 2 months ago

If your teacher asks you to do homework about something that you were not given enough background then challenge that teacher.  I bet that is not the case however.  The sound has echoed several times before 4 seconds.  It has echoed just ONCE more at 4.6 seconds

So it has got to the mountain and back again in 0.6 seconds.

The distance to the mountain and back again is 0.6 * 340 m  And this is ALSO the distance between the two mountains ( because he is in the exact middle.)