Hi all. First post and all that, so I hope I don't do anything wrong, and that if I do, you'll cut me a little slack :P(adsbygoogle = window.adsbygoogle || []).push({});

Anyway, onto the question I'm wanting help with:

A J-shock in a Herbig-Haro object is propagating through neutral hydrogen gas at speed 100km/s. The gas has number density 10^-7 m^-3, and temperature 10^4 K.

a) Calculate the Mach number of the shock, and decide if the strong shock approximation is reasonable.

-- Done this part of the question, and ended up with Mach 7.3*10^-4, and, if I've understood my notes correctly, that the strong shock approximation is reasonable.

b) Calculate the speed and compression of the post shock gas. Work in the shock frame.

-- If I've understood my notes correctly, then the speed of the post shock gas is 1/4 of the speed of the pre-shock gas, giving 25km/s.

For the compression, I'm just guessing, as I've not been able to find that in my notes, but would that just be the pressure? If so, then you've got

P=ma/A,

but I'm not sure as to how to work out the acceleration from what I've been given.

Have I just gone completely down the wrong path, or have I just not noticed something that'd help me work it out easily?

Many thanks in advance for any help that comes my way :)

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# Homework Help: Interstellar Medium: Herbig-Haro Objects

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