A substance loses thermal energy (heat) to the surroundings at a steady rate.
The graph shows how the temperature of the substance changes with time.

What could the portion PQ of the graph represent?

A student wishes to check the upper and the lower fixed points on a Celsius scale thermometer.
She has four beakers P, Q, R and S.
Beaker P contains a mixture of ice and salt.
Beaker Q contains a mixture of ice and water.
Beaker R contains boiling salt solution.
Beaker S contains boiling water.

Which two beakers should she use to check the fixed points?

A liquid at room temperature fills a flask and a glass tube to level X.
The flask is now placed in ice, and the liquid level in the tube falls to level Y.

Why does the level fall?

The melting points of ethanol and mercury are shown.
Which of these two liquids is/ are suitable to use in a liquid-in-glass thermometer to measure temperatures of –50°C and –120°C?

A jug of water is at room temperature.
Several ice cubes at a temperature of 0°C are dropped into the water and they begin to melt immediately.

What happens to the temperature of the water and what happens to the temperature of the ice cubes while they are melting?

An engineer wants to fix a steel washer on to a steel rod. The rod is just too big to fit into the hole of the washer.

How can the engineer fit the washer on to the rod?

The diagram shows electricity cables being put up on a warm day. The cables are left loose between the poles, as shown in the diagram.

Why are the cables left loose?

The diagram shows some ice being used to lower the temperature of some warm water.
What is the main process by which the water at the bottom of the glass becomes cool?

The pressure of a fixed mass of gas in a cylinder is measured. The temperature of the gas in the cylinder is then slowly increased. The volume of the cylinder does not change.

Which graph shows the pressure of the gas during this process?

Two metal blocks X and Y are at room temperature. Each block is heated so that its temperature
rises by 10°C.
The blocks are now allowed to cool back to room temperature.
Block Y has a greater thermal capacity than block X.

Which block needs more thermal (heat) energy to heat it up by 10°C and which block loses more
thermal (heat) energy as it cools back to room temperature?

A long thin bar of copper is heated evenly along its length.

What happens to the bar?

A solid is heated from room temperature. The graph shows how its temperature changes with time as it is heated constantly.
Between which labelled points on the graph is the substance partly solid and partly liquid?

Cold water evaporates as molecules leave it.

Which molecules leave the water and from which part of the water do they leave?

Which row is correct?

The diagram shows a tent made from a new material.

What type of material should the tent be made of to reflect the radiant energy from the Sun?

A night storage heater contains a large block of material that is heated electrically during the
night. During the day the block cools down, releasing thermal energy into the room.

Which thermal capacity and which night-time temperature increase will cause the most energy to be stored by the block?