Question 22N.1.SL.TZ0.28
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1.SL.TZ0.28 |
| Level | SL | Paper | 1 | Time zone | TZ0 |
| Command term | Question number | 28 | Adapted from | N/A |
Water is to be pumped through a vertical height difference of 12.5 m. The pump is driven by a wind turbine that has an efficiency of 50 % and an area swept by the blades of 100 m2. The average wind speed is 5.0 m s−1 and the air density is 1.2 kg m−3.
What is the maximum mass of water that can be pumped every second?
A. 3 kg
B. 30 kg
C. 60 kg
D. 120 kg
[1]
B
The question involved five numerical pieces of data (or even six, including the implied value of g) which is relatively unusual in Paper 1 and caused trouble especially at SL, as indicated by a very low discrimination index. A possible successful strategy is to set up substituted but not evaluated expressions for the power available from the wind and the power required to pump water, followed by partial cancellation of numerical factors on both sides of the equation.