Solar power producing heat
4 marks · NormalThe table shows the temperature rise of water in a solar heating panel at different times of day.
| Time (h) | Temperature rise (°C) |
|---|---|
| 08:00 | 2 |
| 10:00 | 6 |
| 12:00 | 12 |
| 14:00 | 13 |
| 16:00 | 8 |
| 18:00 | 3 |
At what time is the temperature rise greatest?
Between which two times does the water temperature rise the fastest?
Suggest a reason why the rate of water heating falls after 14:00.
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) 14:00 · must show 14:00
(b) 10:00 and 12:00 · must show 10:00 and 12:00
(c) — · must show Sun lower in sky after 14:00, less direct sunlight, energy from Sun decreases/area less exposed
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Identifies 14:00 as the time of greatest temperature rise.
A2 (b) · 1 mark · Correctly finds fastest rise between 10:00 and 12:00.
B1 (c) · 2 marks · States any reasonable reason for the heating rate falling after 14:00 (e.g., Sun is lower so less energy falls on the panel, less direct sunlight).
Worked solution
a) The greatest temperature rise happens at 14:00 (13°C).
b) The fastest increase is between 10:00 (6°C) and 12:00 (12°C), a change of 6°C in two hours.
c) After 14:00, the Sun moves lower in the sky so there is less direct sunlight on the panel; less energy reaches the panel, so water heats more slowly.