A student investigates how the exposed surface area of a hot brass cylinder affects the rate at which it cools.
Two different insulating sleeves are used:
The temperature of the cylinder is measured at t=0t = 0t=0 and then every 20 s20\text{ s}20 s up to 120 s120\text{ s}120 s. The student's results are recorded in Table 1.1:
| Cylinder with Sleeve A | Cylinder with Sleeve B | |
|---|---|---|
| t/t /t/ ... | θ/\theta /θ/ ... | θ/\theta /θ/ ... |
| 000 | 85.085.085.0 | 85.085.085.0 |
| 79.579.579.5 | 82.082.082.0 | |
| 74.574.574.5 | 79.579.579.5 | |
| 70.070.070.0 | 77.077.077.0 | |
| 66.066.066.0 | 75.075.075.0 | |
| 62.562.562.5 | 73.073.073.0 | |
| 59.559.559.5 | 71.571.571.5 |
Complete the headings and the time ttt column in Table 1.1.
Write a conclusion to this experiment, stating for which sleeve the cooling rate is greater. Explain your answer with reference to the temperature values in Table 1.1.
Suggest a change to the apparatus or setup that could produce a greater difference between the cooling rates of the cylinder with Sleeve A and Sleeve B. Explain why this change would produce a greater difference.
A student thinks that the cooling rate is directly proportional to the percentage of the surface area uncovered. To investigate this, they plan to plot a graph of cooling rate against the percentage of uncovered area.
Describe how the graph line will show whether the cooling rate and the percentage of uncovered area are directly proportional.
Suggest one factor, other than the surrounding room temperature, that should be kept constant in repeats of this experiment to ensure a fair comparison.
301 exam-style questions on CIE IGCSE Physics 2.3 Transfer of thermal energy, covering 2.3.1a Thermal conductors and thermal insulators, 2.3.1b Explaining thermal conduction, 2.3.2 Convection, 2.3.3a Thermal radiation, 2.3.3b Surface colour and texture, 2.3.3c Rate of emission and absorption of radiation, and 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.