Shock Wave Questions: Calculating Speed & Intensity

[nicholas0211510]

How would one calculate the speed of a shock wave or intensity? For example, let's say something with a mass of 10 kg, with a velocity of 1000 m/s, travling in a straight line ,in Earth's atmosphere, at sea level . what formulas would one use to figure this out? Thanks in advanced

 

[boneh3ad]

Mass is not as important as shape. That said, there still isn't any general formula to calculate it exactly and the shock strength will almost definitely vary at different points along the wave. Still, you can get a "worst case" estimate by using the normal shock relations to get the strength. It's speed is just going to be the same as the body.

 

[nicholas0211510]

Ah, so the shock wave behind it will have a equal speed as the object that created it? So if somthing is moving at mach 3 , the shock wave will be mach 3?

 

[sophiecentaur]

Ah, so the shock wave behind it will have a equal speed as the object that created it? So if somthing is moving at mach 3 , the shock wave will be mach 3?

As far as I know, the shock wave is only the region where the air is being made to move 'faster than sound'. Once the object has passed by, the shockwave becomes just a sound wave. The air cannot support any higher speed than that without the energy supplied by the passing object and that dissipates pretty soon.

 

[cjl]

Ah, so the shock wave behind it will have a equal speed as the object that created it? So if somthing is moving at mach 3 , the shock wave will be mach 3?

Correct, at least near the aircraft.

 

[boneh3ad]

I'd also like to point out that saying the shock wave "behind" the object is misleading. The strongest shock wave(s) will be in front of (or attached to the front of) the object. There may or may not be anything behind the object depending on the shape.