In a gas, the particles move around at high speed. By doing this they collide with the sides of their container and produce a force. This is the force that keeps balloons and tires inflated. We call it gas pressure.
There are two ways to increase gas pressure. The first is to add more gas particles. More gas particles can collide with the walls more often which increases the pressure. This is what happens when you blow up a balloon or pump up your bike tire. You add more air particles.
The second way to increase gas pressure is to increase the temperature. When it is warmer, gas particles gain more energy and can move around faster. At a higher speed the particles collide with the walls more often and the pressure increases.
If you reduce the temperature, the opposite happens. The gas particles move slower and collide with the walls less frequently. This decreases the gas pressure.
Questions:
- What causes gas pressure?
- How can you increase gas pressure? Describe both ways.
- How can you decrease gas pressure?
- What would happen if I put a party balloon into the sun on a hot day? Why?
- What would happen if I put a party balloon in a freezer? Why?
A tang of science 