5 ms·
Haha, that's right, I forgot that Mach is a measurement of speed through a fluid and the local speed of sound. Obviously, Mach 7 on the Moon is greater than Ma
by politician 12y ago
Haha, that's right, I forgot that Mach is a measurement of speed through a fluid and the local speed of sound. Obviously, Mach 7 on the Moon is greater than Mach 7 on Earth. I guess that means we can fire larger payloads with the same platform.
- jerf 12y ago"Obviously, Mach 7 on the Moon is greater than Mach 7 on Earth." Well... Mach 7 through the Moon's atmosphere is probably best described as "undefined" rather than greater than anything....
- politician 12y agoLunar atmospheric pressure is non-zero [1] (but to your point, it's really really small). [1] http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html
- zachrose 12y agoWould very low pressure mean that Mach 1 on the Moon is be much faster than on Earth?
- tsm 12y agoYes, exactly
- lutorm 12y agoActually, the speed of sound through a gas only depends on temperature, not pressure. (But the Moon's "atmosphere" can hardly be described as a gas anyway...)
- ecma 12y agoAt least google stuff like this before posting it (and maybe include a reference) because this is unequivocally wrong. Speed of sound in a gas is calculated with the Newton-Laplace equation [1] which refers to K, the bulk modulus which is derived from the pressure and the adiabatic constant for ideal gases. It also involves rho, the density of the medium which is why gases and non-gaseous fluids have very different results. [1] http://en.m.wikipedia.org/wiki/Speed_of_sound#Equations http://en.m.wikipedia.org/wiki/Speed_of_sound#Equations