9

• Air particles in the tyre move quickly in ___ directions.

  random
• When the tyre is at the correct pressure, pumping more air into the tyre causes the pressure to increase further. The volume and temperature of the air in the tyre do not change. Explain why the pressure increases as more air is pumped into the tyre.

  More particles in the tyre means greater number of collisions with the tyre per second.
• The air pressure in a car tyre changes if the temperature of the air in the tyre increases. Explain why.

  As temperature increases, particles gain more kinetic energy causing more collisions. These collisions also come with more force which causes greater pressure.