Why does a molecule of a gas move at high speed?

Answer 1

If the force of the engines is constant, then the rocket's acceleration could increase

as time goes on because its mass is decreasing ... it's losing the mass of all that fuel

that's burning to keep the engines running.

Answer 2

The whole motivating action that goes on in a rocket is based on Newton's law that "for every action there is an equal and opposite reaction"

In a rocket the gases exiting the nozzle represent one of these actions. The force it provides comes from the momentum of the exhaust gases, which in turn depends on the speed of the gas and the mass of the gas. The rocket represents the other momentum force.

Mathematically: (Mass of the gas)x(Speed of gas)=(Mass of the Rocket)x(-1)x(Speed of the rocket) Note that the (-1) takes care of the "and opposite" as the rocket is moving in the other direction.

As you can guess the mass of the rocket exceeds the mass of the gases at any instant. For the gases to move the rocket in a direction, they have to be moving in the opposite direction at a very high speed. The gases have to move very fast to move the rocket reasonably fast.

Now, why does the rocket accelerate?

As the rocket burns up its fuel it gets lighter. The fuel burning system is designed to burn fuel at a given rate (make a steady flow of exhaust mass). From the equation, the speed and mass of the exhaust stays constant but the mass of the rocket reduces, so the rocket has to go faster to make the equality hold true.

Answer 3

Molecules of a gas move at high speeds because they have kinetic energy, which is the energy of motion. This kinetic energy is a result of thermal energy, which causes the molecules to vibrate and move around rapidly in random directions.

Answer 4

It has more energy within it which speeds it up causing it to fly faster and bounce harder off of other molecules thus pushing them farther apart creating a gas.