Physics 5054 · O Level · Transfer of thermal energy

Transfer of thermal energy — practice question

A student examines how rapidly water cools near the top and near the bottom of a beaker of hot water. The apparatus setup is shown in Figs. 2.1 and 2.3.
(a(i))[1]

State the temperature at time $t = 0$, rounded to the nearest $0.5^\circ\text{C}$.

(a(ii))[1]

Explain why the student delays for $30\,\text{s}$ before taking the initial temperature of the hot water.

(b(i))[3]

Calculate the average rate of cooling $P_T$ for the hot water at the top of the beaker by using $\text{average rate of cooling} = \frac{\text{decrease in temperature of the water}}{\text{time taken}}$. Give your answer to $2$ significant figures and state the unit.

(b(ii))[1]

Using the data in Table 2.1, calculate the average rate of cooling $P_B$ for the hot water at the bottom of the beaker.

(c(i))[1]

Use your answers to (b)(i) and (b)(ii) to suggest why a hot liquid ought to be stirred before its temperature is measured.

(c(ii))[1]

State one feature of the apparatus arrangement in this experiment that helps the thermometer to be read accurately.

(d)[1]

Suggest one variable that should remain constant when the experiment is repeated to check the results.

(e)[1]

Predict the temperature of the water in the beaker after $30$ minutes.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: 85.5^{\circ}\text{C}

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