Final answer:
The helium gas flowing through a well-insulated nozzle experiences an increase in velocity, which is the purpose of the nozzle. This occurs due to the Bernoulli effect, where the gas's kinetic energy increases as it passes through the nozzle, reducing its pressure and subsequently increasing its speed.
Step-by-step explanation:
The purpose of a nozzle when helium gas, or any gas, flows through it is to increase the gas's velocity. According to the principles of fluid dynamics, specifically the Bernoulli effect, as a gas moves through a narrower section of a pipe or nozzle, its speed increases. This is due to the conservation of energy, where the kinetic energy of the gas increases at the cost of its potential energy, which is related to pressure. So, in a well-insulated nozzle where heat loss is negligible, and assuming an ideal gas scenario, the decrease in pressure results in an increase in the velocity of the gas as it exits the nozzle.
When discussing pressure, it's the force per unit area exerted by the gas on the surfaces it comes into contact with. Gases create pressure by the constant movement and collision of particles with the walls of their container. If gas particles stopped moving altogether, there would effectively be no pressure exerted since pressure arises from the motion and collisions of these particles. Moreover, temperature affects pressure as they are directly correlated; increasing the temperature of a gas will result in an increase in pressure if the volume is held constant, due to the increased kinetic energy and hence the more forceful and frequent collisions of gas particles with container walls.