State why two objects at the same temperature are said to be in thermal equilibrium.
Fig. 3.1 displays how the densities of mercury and water change with temperature between $0\,^{\circ}\text{C}$ and $100\,^{\circ}\text{C}$. Temperature can be found from how the density of a liquid varies with temperature. Suggest why, for measuring temperature over this temperature range:
mercury is the suitable liquid.
water is unsuitable.
A beaker holds a liquid of mass $120\,\text{g}$. Thermal energy is delivered to the liquid at a rate of $810\,\text{W}$. The beaker has a mass of $42\,\text{g}$ and a specific heat capacity of $0.84\,\text{J g}^{-1}\,\text{K}^{-1}$. The beaker and the liquid are in thermal equilibrium with each other at all times and are insulated from the surroundings. Fig. 3.2 shows how the temperature of the liquid varies with time $t$.
State the boiling temperature, in $^{\circ}\text{C}$, of the liquid.
Determine the specific heat capacity, in $\text{J g}^{-1}\,\text{K}^{-1}$, of the liquid.
In (c), the experiment is repeated with water instead of the liquid used in (c). The mass of liquid used, the power supplied, and the initial temperature all remain unchanged. The specific heat capacity of water is approximately twice that of the liquid in (c). Water boils at $100\,^{\circ}\text{C}$. On Fig. 3.2, sketch how the temperature of the water changes with time $t$ between $t = 0$ and $t = 60\,\text{s}$. No numerical calculations are required.