Why Do You Use A Helium Gun

The sound velocity of the gas is calculated as v = (kRT) ^ 0.5 where T is the temperature, k is 1.76 for the monoatomic gas such as helium, and 1.4 for the diatomic gas such as hydrogen, and R is the unit mass gas constant equal to one. The number of moles of kilogram gas is multiplied by 8.314.

Therefore, helium is accelerated because it has a very small molar mass and it is a monoatomic gas that makes its sound velocity very high (which is why it can be used to change the sound of a helium balloon). The above is a theoretical derivation, you can also simply understand this.

When the high pressure gas pushes the material forward, the pressure of the high pressure gas must also push the gas molecules to advance at a high speed, so in the same situation, the small gas molecular mass can better transfer the kinetic energy to the substance to be propelled.