AS Daily A Level Physics question
Two perpendicular forces act on a trolley on a smooth bench: 3.6 N due east and 4.8 N due north. What is the magnitude of the resultant force?
Answer
The correct answer is D.
Correct: D — 6.0 N. For perpendicular forces, the magnitude combines by squaring and adding the components: 3.6^2 + 4.8^2 = 12.96 + 23.04 = 36, so the resultant is sqrt(36) = 6.0 N. A adds the magnitudes as if they were scalars (3.6 + 4.8 = 8.4), ignoring the perpendicular directions. B uses an incorrect SI unit for force; kilograms measure mass, not force. C likely rounds the components first (3.6 → 4 and 4.8 → 5) then combines to give about 6.4 N; rounding should be left to the end. D correctly combines perpendicular vectors and keeps units as newtons.