Object A is at \(310\,\mathrm{K}\) and object B is at \(290\,\mathrm{K}\). They are placed in thermal contact. What is the direction of net heat transfer at first?

A thermometer is placed in a liquid and eventually gives a steady reading of \(36.5\,{}^\circ\mathrm{C}\). What temperature can be assigned to the liquid at that stage?

Systems A and B are each separately in thermal equilibrium with system C. What does the zeroth law imply about A and B?

Two metal blocks have the same temperature, but one block has twice the mass of the other. Are they in thermal equilibrium if placed in contact? Does that require equal internal energies?

A heat current is observed from system X to system Y when they are connected by a conducting link. Compare \(T_X\) and \(T_Y\).

A tiny hot droplet is measured with a much larger cold thermometer. Explain why the final steady thermometer reading may be lower than the droplet's original temperature.

A sensor in a furnace currently reads \(480\,\mathrm{K}\), but its reading is still increasing. Can \(480\,\mathrm{K}\) be taken as the furnace temperature? Explain using thermal equilibrium.

System A is in equilibrium with thermometer C at \(295\,\mathrm{K}\). Later, without changing C's calibration, system B is brought into equilibrium with the same thermometer and gives the same reading. Explain why A and B have the same temperature even though they never touched.

An isolated pair of objects is left in thermal contact until all macroscopic changes stop. State the condition on their temperatures and on the net heat current between them. Does microscopic energy exchange have to stop?

A proposed thermometer property \(X\) gives the same value for two systems whenever a conducting wall between them produces no net heat transfer. Explain why this property can be used to build a temperature scale, and name the physical law behind the argument.