Further Mathematics Paper 2, May/June. 2015

Question 8

Forces of magnitude 3N, 4N and 2N act along the vectors j, -i + j and i + j respectively. Calculate, correct to one decimal place, the magnitude of the resultant of the forces.


This question was reported to be poorly attempted by majority of the candidates who attempted it. Candidates exhibited poor knowledge of vectors. Candidates were expected to either resolve the forces or find the unit vectors in each of the given directions multiply them by the magnitude of the forces and thereafter find the magnitude of the resultant. By resolving the forces we obtain
R =  +  +  =  +  + = . Therefore, magnitude of R = |R| =  = 7.4 N, correct to 1 decimal place.