Need Help With this Physics Problem (Please)

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A supersonic jet traveling at Mach 3 at an altitude of 20,000 m creates a shockwave that a ground observer will encounter after a calculated time. The speed of sound is given as 345 m/s, leading to the conclusion that the shockwave takes approximately 58 seconds to reach the observer. During this time, the jet will have traveled 60,000 m horizontally. The Pythagorean theorem is used to determine the straight-line distance between the observer and the jet when the shockwave is heard. The confusion regarding the Doppler Effect's relevance to this problem was clarified during the discussion.
jpnnngtn
This is the problem, anyone who can help me, please respond.

A supersonic jet traveling at Mach 3 (means that the speed of the jet is three times faster than the speed of sound in air) at an altitude of 20,000 m is directly overhead at t(time) = 0. How long will it be before the ground observer encounters the shockwave? Where will the plane be when it is finally heard? (Assume that the speed of sound in air is uniform at 345 m/s)


This problem is listed under the Doppler Effect in my textbook
 
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Looks pretty easy to me. I BELIEVE that the shock wave itself moves at the speed of sound (if that's incorrect I'm sure there will be people happy to jump on me with both feet :smile:).

Since v= d/t, t= d/v: 20000 m/345 m/sec.= how many seconds?

In the time that the shockwave takes to move the 20000 feet down, the jet, at three times the speed, will have moved three times as far, 60000 feet, horizontally. To find the straight-line distance between the person who hears the shock wave and the jet, use the Pythagorean theorem.

(I don't see how "Doppler Effect" has anything to do with it.)
 
you're right. Thank you. You have been most helpful. I think I was just confused because the problem was listed under the group of "Doppler Effect" problems.
 
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