I was watching an XKCD “What-If” video recently and Randal off-handedly mentions the title fact as a given. Upon a further Google search I see explanations about why sound moves faster in liquids than gasses but nothing for my specific question. Is there an intuitive explanation for that fact or is it just one of those weird observable facts with no clear explanation
I don’t know how this works, but wouldn’t the exhaust of the jet be moving at or slower than the speed of sound relative to the other particles in the exhaust. Sure, compared to other particles it’s moving faster, but that doesn’t really matter if we’re only looking at the exhaust. It’s not doing anything differently, though the exhaust and outside particles will have to interact at the boundary.
Precisely. It’s those boundary areas where the jet and the medium interact where it gets complicated.