Brownian motion serves as key physical evidence supporting the kinetic theory of matter.
State one practical method by which Brownian motion can be observed within a school laboratory.
Explain how the observations made in this demonstration provide direct evidence that fluids (liquids or gases) are composed of extremely small, rapidly moving particles.
Using the kinetic theory of matter, explain the mechanism by which a gas confined inside a rigid vessel exerts pressure on its surrounding walls.
A heavy delivery van's tyre is inflated to a pressure of 450 kPa450\text{ kPa}450 kPa. The flat area of contact between the tyre and the road surface is 0.018 m20.018\text{ m}^20.018 m2.
State the equation linking pressure, force, and area.
Calculate the total downward force that the tyre exerts on the road surface.
After a long journey, the air inside the tyre warms up due to friction with the road. Explain how this temperature change affects the contact area between the tyre and the ground, assuming that the volume of the tyre and the weight acting on the wheel remain constant.
