AQA GCSE Physics: Particle Model of Matter

A sealed, rigid metal can contains a fixed amount of gas. The can is left in the Sun and the gas inside it gets hotter. The volume of the can does not change.

Using the particle model, explain why the pressure of the gas inside the can increases as its temperature rises. (6 marks)

A student measures a regular metal block. Its mass is 216 g and its volume is 80 cm³.

(a) Calculate the density of the metal, in g/cm³. Use $\rho = \dfrac{m}{V}$ρ=Vm​. Show your working and give the unit. (2 marks)

(b) Convert this density into kg/m³. (1 mark)

(c) The density of water is 1000 kg/m³. State whether the block would float or sink in water, and give a reason. (1 mark)

An insulated copper block of mass 2.0 kg is heated by an electric heater. The temperature of the block rises by 15 °C. The specific heat capacity of copper is 385 J/kg °C.

Calculate the energy transferred to the copper block. Use $E = mc\,\Delta\theta$E=mcΔθ. Show your working and give the unit. (3 marks)

A scuba diver descends in sea water. The pressure acting on the diver increases with depth. (This is Higher-tier content.)

The pressure due to a column of liquid is given by $p = \rho g h$p=ρgh, where the density of sea water is $\rho = 1030\ \text{kg/m}^3$ρ=1030 kg/m3 and $g = 9.8\ \text{N/kg}$g=9.8 N/kg.

(a) Calculate the pressure due to the sea water at a depth of $h = 20\ \text{m}$h=20 m. Show your working and give the unit. (2 marks)

(b) State and explain what happens to this pressure if the diver descends deeper. (1 mark)

When a substance is melting, energy is supplied to it but its temperature stays constant.

Explain, in terms of the particles, why the temperature does not rise while a solid is melting, even though energy is still being supplied. (2 marks)

Ice, liquid water and water vapour (steam) are the three states of the same substance.

Name the change of state in which a liquid turns into a gas. (1 mark)