Question 22N.1A.SL.TZ0.21
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.SL.TZ0.21 |
| Level | SL | Paper | 1A | Time zone | TZ0 |
| Command term | Question number | 21 | Adapted from | N/A |
A mass attached to a string rotates in a gravitational field with a constant period in a vertical plane.
How do the speed of the mass and the tension of the string compare at P and Q?
[1]
D
One of the most challenging questions in this paper. Incorrect alternatives A and B were the ones most often picked by the candidates. However, both these alternatives can be easily eliminated by the argument that the tension is always along the string so it doesn't do any work on the mass, but the gravitational force does so the speed must be greater at Q.
It is useful to compare this question to question 4 in Paper 2, in which a mass is again moving in a vertical circle but it is attached to a rigid rod rather than a string. The rod exerts a force that is not necessarily towards the centre of the circle, therefore the mass can move with a constant speed which is not the case for a mass attached to a flexible string.