1. The physics of rockets

2. Learning objectives Know how pressure builds up in a rocket
Know how increases in pressure cause the rocket to lift off.
Know how Newton’s 3rd Law and momentum relates to how a rocket works.

3. Success criteria
Explain how pressure of a gas can be increased, using a particle model (Grade C)
Explain how equal and opposite forces cause a rocket to launch (Grade B)
Explain pressure in terms of rate of change momentum of particles (Grade A)

4. Kinetic theory of gases
Particles in a gas move randomly.
They collide with each other and the walls of a container, exerting a pressure.
What could you change to increase the pressure of the gas?

5. Change the volume of the container:
Change the temperature of the gas:

6. How a real rocket works The gas in a rocket is hydrogen.
The hydrogen is burnt with oxygen in the combustion chamber.
Hot gases build up, creating a high pressure.
Some gas particles are forced downwards out of the base of the rocket.
There is an equal and opposite force upwards on the rocket.

7. How a real rocket works continued
Pressure causes the hot gases to push against the rocket.
The rocket pushes back against the gas.
Action Force
Reaction Force

8. Plenary
In groups, label the picture to explain how the rocket lifts off.
Use as many key words and ideas from the lesson as you can.