A-LevelMathematicsMechanics9709/41 · May/June 2020 · Q47 Marks
The diagram shows a ring of mass 0.1 kg threaded on a fixed horizontal rod. The rod is rough and the coefficient of friction between the ring and the rod is 0.8. A force of magnitude T N acts on the ring in a direction at 30° to the rod, downwards in the vertical plane containing the rod. Initially the ring is at rest. [The diagram]
- (a)Find the greatest value of T for which the ring remains at rest.[4]
- (b)Find the acceleration of the ring when T = 3.[3]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2020). The mark or mark type is shown in brackets.
- [M1] Resolving forces in either direction
- [A1] R = T sin30 + 0.1g, F = T cos30
- [M1] T cos30 = 0.8 (T sin30 + 0.1g)
- [A1] T = 1.72 (1.7166...)
- [B1] R = 3sin30 + 0.1g
- [M1] 3 cos30 - 0.8(3sin30 + 0.1g) = 0.1a
- [A1] a = 5.98 ms⁻² (5.9807...)
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →