A-LevelMathematicsMechanics9709/42 · Feb/Mar 2019 · Q36 Marks
Four coplanar forces of magnitudes FN, 5 N, 25 N and 15 N are acting at a point P in the directions shown in the diagram. Given that the forces are in equilibrium, find the values of F and α.
- Four coplanar forces of magnitudes FN, 5 N, 25 N and 15 N are acting at a point P in the directions shown in the diagram. Given that the forces are in equilibrium, find the values of F and α.[6]
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 (Feb/Mar 2019). The mark or mark type is shown in brackets.
- [M1] Attempt to resolve forces horizontally or vertically
- [A1] F cos α = 15 cos 20 – 5 (= 9.095...)
- [A1] F sin α = 15 sin 20 + 25 (= 30.13....)
- [M1] Use Pythagoras or trigonometry to find F
- [M1] Use trigonometry to find α
- [A1] α = 73.2 and F = 31.5
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