Question 22M.2.SL.TZ1.2b
| Date | May 2022 | Marks available | [Maximum mark: 2] | Reference code | 22M.2.SL.TZ1.2b |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Outline | Question number | b | Adapted from | N/A |
Cold milk enters a small sterilizing unit and flows over an electrical heating element.
The temperature of the milk is raised from 11 °C to 84 °C. A mass of 55 g of milk enters the sterilizing unit every second.
Specific heat capacity of milk = 3.9 kJ kg−1 K−1
Outline whether your answer to (a) is likely to overestimate or underestimate the power input.
[2]
Underestimate / more energy or power required ✓
because energy transferred as heat / thermal energy is lost «to surroundings or electrical components» ✓
Do not allow general term “energy” or “power” for MP2.
Many candidates recognized that this was an underestimate of the total energy but failed to provide an adequate reason. Many gave generic responses (such as "some power will be lost"/not 100% efficient) without discussing the specific form of energy lost (e.g. heat energy).
