Physics (AS & A Level) · Feb / March 2024 · Paper 12 · Question 13

A rod is pivoted at one end. Initially the angle θ of the rod to the horizontal is 0°. The weight of the rod causes a moment M about the pivot. The rod is then rotated in the vertical plane so that the angle θ of the rod increases from 0° to 180°. Which graph shows the variation of M with θ?

1. AGraph A: M constant at a positive value for all θ from 0° to 180°
2. BGraph B: M starts at a positive maximum, decreases to zero at 90°, then increases back to the same maximum at 180°
3. CGraph C: M starts at a positive maximum and decreases linearly, crossing zero at 90° and becoming negative at 180°
4. DGraph D: M starts at a positive maximum, decreases to zero at 90°, then becomes negative at 180°

As printed in the paper