Paper 2 Thermal Physics Route Drills

Q1 Choosing the correct model

A question involves heating ice at $0^{\circ }\mathrm{C}$ until it becomes water at $20^{\circ }\mathrm{C}$.

1. State the two thermal models needed. [2]
2. Explain why temperature does not rise during melting. [2]
3. Write an energy-accounting expression for the total energy required. [2]

Q2 Gas and temperature

A fixed mass of gas is kept at constant volume while temperature changes from $20^{\circ }\mathrm{C}$ to $80^{\circ }\mathrm{C}$.

1. Explain why kelvin must be used. [1]
2. Calculate the ratio $p_2/p_1$. [2]
3. Explain the pressure increase using kinetic theory. [3]

Q3 First-law classification

A gas is compressed rapidly so that little energy is transferred by heating.

1. State the approximate process type. [1]
2. Explain the sign of work done on the gas. [2]
3. State the effect on internal energy and temperature for an ideal gas. [2]