Estimating Jet Speed Using Sound and Light

[DANIELLYMA]

Homework Statement

When a jet plane flies overhead at a high altitude, the sound from the engines can be heard, but the sound seems to come from well behind the aircraft. If you knew the altitude of the jet to be 10,000m, how could you estimate the speed of it? Show this using an example.

Homework Equations

c = 3.00*10^8m/s?

The Attempt at a Solution

I asked my teacher this question, but he told me to think about it. He hinted at using the speed of light, speed of sound, and a stop watch. I tried drawing a diagram showing how the person would see the plane first before hearing the engine. I know sound travels slower than light, but I don't know what to do next.

 

[Johnny Blade]

The aircraft is traveling faster than the speed of the sound. Another good example of this is lightning and thunder. You see the lightning first because the speed of light is faster than the speed of sound (the thunder). In my class of physics 11 we finished that module last week.

 

[DANIELLYMA]

The aircraft is traveling faster than the speed of the sound. Another good example of this is lightning and thunder. You see the lightning first because the speed of light is faster than the speed of sound (the thunder). In my class of physics 11 we finished that module last week.

Thanks for the answer, but is there a way to estimate the speed of the jet?

 

[Johnny Blade]

Not if there's no more data. The speed is 1 mach or higher.

 

[DANIELLYMA]

I think it can be figured out because as I previously posted, my teacher hinted at using the speed of sound, speed of light, and a stop watch.

 

[DANIELLYMA]

Does anyone have a solution?