Sound and Frequency Help!

Question

1. A military jet is dying at an altitude of 12,000 meters and a speed of 600 m/sec. If the air temperature is exactly 0°C, calculate:

a) How far behind the jet its sound wave begins

b) How long the sound takes to reach the ground

c) How far the plane flies while the sound travels to the ground

d) The total distance between the actual location of the plane apparent location of the sound it makes as heard from the ground

2. A shepherd shoots at a coyote standing near the base of a steep cliff. If the muzzle velocity of the rifle is 325 m/sec, will the coyote hear the shot before the bullet reaches him? (Air temperature is 20°C)

Answer 1

Hello Ivan M.,

You will need data on the speed of sound at 0C. It's somewhere around 330 m s^-1.Then you can start drawing your vector diagram for the movement of the sound wave (it propagates laterally to the line of travel of the jet, but describes a conical shape as this is ~ Mach 2.) and the movement of the jet. The two speeds form the (trig) tangent for the cone angle (angle from edge to centeraxis of the cone). Every aspect of the problem is solved from that vector triangle.

I can't help but wonder: was the coyote distracted by the sonic boom as it was being shot? (you need the speed of sound at 20C). It's unlikely that the coyote would hear the gunshot, at a substantial distance?

Was the shepherd a Woodpecker, by any odd chance?

-- Cheers, --Mr. d.