Fig. 3.1 shows a flat tyre on a car. The tyre needs to be inflated.
The force exerted by the flat tyre on the road is 1350 N.
The area of the flat tyre in contact with the road is 0.0070 m².
(a)(i)Calculate the pressure exerted by the flat tyre on the road.
Air is pumped into the tyre to inflate it. This increases the pressure inside. The force exerted by the tyre on the road does not change.
(a)(ii)State how the area of the tyre in contact with the road changes.
Inside the inflated tyre, a particle of air collides against the wall of the tyre.
(b)(i)Define ‘momentum’.
(b)(ii)Using ideas about momentum, explain why there is a force on the wall of the tyre as the particle collides with it.
As the car moves, the temperature of the air inside the tyre increases. The increase in temperature causes an increase in the pressure of the air.
(c)Using ideas about particles, explain why the pressure increases.