A-LevelMathematicsMechanics9709/42 · Oct/Nov 2017 · Q15 Marks
A particle of mass 0.2 kg is resting in equilibrium on a rough plane inclined at 20° to the horizontal.
- (i)Show that the friction force acting on the particle is 0.684 N, correct to 3 significant figures.[1]
- (ii)The coefficient of friction between the particle and the plane is 0.6. A force of magnitude 0.9 N is applied to the particle down a line of greatest slope of the plane. The particle accelerates down the plane. Find this acceleration.[4]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.
- [B1] F = 0.2g sin 20 = 0.684 N AG
- [B1] R = 0.2g cos 20
- [M1] F = μR [= 0.6 × 0.2g cos 20] F = 1.1276...
- [M1] [0.9 + 0.2g sin 20 – F = 0.2a] Use of Newton's 2nd law along the plane (4 relevant terms)
- [A1] a = 2.28 ms-2
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