mean speed of molecules

The mean speed of hydrogen molecules at a temperature of 3100° Celsius in a closed room in a usual time frame (say one second) is 0 m/sec (the room is closed). Instantaneous mean speed of one hydrogen molecule along very short distance (comparable to it's size) at 3100° Celsius is near 9000 meter per second!

*This molecule movement is what make
possible transmission of the sound and usual pressure laws and sub
Mach aerodynamic laws.*

If you drill a small hole in
the room's wall with a width around an atom size, hydrogen atoms will
get off the closed room at a speed near the mean instantaneous speed
and at 90° of the wall, but there will be only one at a time.

So according to Newton's law the impulse will be very small even if the exhaust speed is far above usual ones.

If you drill a large hole in the room's wall with a width of 10 cm, hydrogen atoms will get off the closed room at a speed near the mean instantaneous speed but at angles varying between 0+ degrees and 90° of the wall, with an average of 45° and a mean exhaust speed of half the mean instantaneous speed..

Instantaneous mean speed of one hydrogen molecule at various temperatures.

Celsius Temperature |
-73 |
227 |
527 |
1127 |
1627 |
2127 |
2627 |
3127 |

Kelvin Temperature |
300 |
600 |
900 |
1500 |
2000 |
2500 |
3000 |
3500 |

Instantaneous mean speed of a hydrogen molecule in m/sec |
2726 |
3855 |
4721 |
6095 |
7038 |
7868 |
8619 |
9310 |

But this is not the exhaust speed, it's only the mean speed you can measure.