Further Mathematics Paper 2, May/June. 2010
 Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Main
Weakness/Remedies
Strength

Question 7

The position vector of a particle of mass 3 kg moving along a space curve is given by r = (4t3 - () i - (2t2 - t) j at any time t seconds. Find the force acting on it at t = 2 seconds.

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Observation

Candidates were expected to recall that force = mass x acceleration. They were expected to obtain the acceleration from the position vectorr = (4t3 - t2) i - (2( -t) j by finding the second derivative of r with respect to t to obtain dZzT = (24t - 2)i - 4j . At t = 2, dZzT = (24(2) - 2)i - 4j which gave 46i - 4j.
dt                                                 dt
Thus, r = ma = 3(46i - 4j) = 138i -12j.

Majority of the candidates were reported to have performed poorly in this question which the report attributed to their inability to recall the relation: force = mass x acceleration ( f = ma).