Define specific heat capacity in terms of thermal energy and unit mass.
A student uses the apparatus shown in Fig. 3.1 to find the specific heat capacity of a liquid. The liquid enters the tube at a steady temperature of $19.5^\circ\text{C}$ and exits at $25.5^\circ\text{C}$. The mass of liquid passing through the tube per unit time is $m$, and electrical power $P$ is supplied to the heating coil. The student varies $m$ and then adjusts $P$ until the temperature of the liquid leaving the tube is $25.5^\circ\text{C}$. The results displayed in Fig. 3.2 are recorded.
Suggest why the student records data for two different values of $m$ instead of just one.
Calculate the specific heat capacity of the liquid. Show your working.
When the heating coil in (b) dissipates $33.3\text{ W}$ of power, the potential difference $V$ across the coil is given by $V = 27.0\sin(395t)$. The potential difference is measured in volts and the time $t$ is measured in seconds. Determine the resistance of the coil.