DP Physics (last assessment 2024)
Question 19M.3.SL.TZ2.d
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.3.SL.TZ2.d |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Suggest | Question number | d | Adapted from | N/A |
d.
[Maximum mark: 2]
19M.3.SL.TZ2.d
A heat pump is modelled by the cycle A→B→C→A.
The heat pump transfers thermal energy to the interior of a building during processes C→A and A→B and absorbs thermal energy from the environment during process B→C. The working substance is an ideal gas.
Suggest why this cycle is not a suitable model for a working heat pump.
[2]
Markscheme
the temperature changes in the cycle are too large ✔
the cycle takes too long «because it contains an isothermal stage» ✔
energy/power output would be too small ✔
Examiners report
Because the question was about a heat pump rather than a heat engine very few answers were correct. Only a very small number of candidates mentioned the fact that the isothermal change would take an impracticably long time.
