Energy Transfers
3 marks · NormalA student investigates how the colour of a can affects how much heat it radiates. She heats two cans, one painted matt black and one painted shiny white, to the same temperature and then measures their temperatures as they cool.
Their results are shown in the table:
| Time (min) | Matt black can (°C) | Shiny white can (°C) |
|---|---|---|
| 0 | 80 | 80 |
| 2 | 72 | 75 |
| 4 | 65 | 71 |
| 6 | 59 | 68 |
| 8 | 54 | 66 |
Plot a line graph of the temperature of each can against time. Draw both lines on the same axes. Label your axes.
State which can radiates heat faster and explain why, using the graph.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Line graph with both sets of points plotted: time (min) on x-axis, temperature (°C) on y-axis, one line for matt black, one for shiny white. · must show Both lines; correct axes; labelled; all points plotted from table
(b) The matt black can radiates heat faster, as it cools more than the shiny white can in the same time. The graph shows a steeper temperature drop for the matt black can.
Must show: data points plotted accurately for both cans, axes labelled: time (min), temperature (°C)
Common mistakes: Swapping axes; Omitting line for one can
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Plots all points for both cans accurately; axes labelled correctly.
B1 (a) · 1 mark · Draws clear lines through or between points for each can, both on same axes; keys/labels distinguished.
B1 (b) · 1 mark · Identifies matt black can radiates heat faster by larger temperature drop; links to graph evidence.
Worked solution
(b) The matt black can cools the most after 8 minutes, indicating it radiates heat more quickly than the shiny white can. The line for the matt black can drops more steeply.