A-LevelMathematicsMechanics9709/51 · May/June 2019 · Q35 Marks
The diagram shows the cross-section through the centre of mass of a uniform solid object. The object is a cylinder of radius 0.2 m and length 0.7m, from which a hemisphere of radius 0.2 m has been removed at one end. The point A is the centre of the plane face at the other end of the object. Find the distance of the centre of mass of the object from A. [The volume of a hemisphere is ²/₃πr³]. [Figure 3.1]
- Find the distance of the centre of mass of the object from A.[5]
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 2019). The mark or mark type is shown in brackets.
- [B1] Both volumes required for B1
- [B1] Distance of centre of mass from object base = 0.7-³⁄₈ × 0.2 (= 0.625)
- [M1A1] Take moments about the plane face
- [A1] x = 0.285 m
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