Brownian motion provides experimental evidence for the particle theory of matter.
State one example of how Brownian motion can be demonstrated in a school laboratory.
Explain how this demonstration provides evidence that gases or liquids are made of tiny, moving particles.
Using ideas about particles, explain how a gas inside a container exerts pressure on the walls.
A bicycle tyre exerts a pressure of 380 kPa380\text{ kPa}380 kPa on the ground. The contact area between the tyre and the ground is 0.0025 m20.0025\text{ m}^20.0025 m2.
State the equation linking pressure, force, and area.
Calculate the force that the tyre exerts on the ground.
As the bicycle is ridden, the air inside the tyre warms up. Explain how this temperature change affects the contact area between the tyre and the ground, assuming the volume of the tyre and the load on the wheel remain constant.
