JAMB Physics 2011 Paper

Concept:The resultant of two vectors that act at right angles to each other is obtained using Pythagoras' theorem.Explanation:From the diagram, the two perpendicular vectors have magnitudes $6.0\,\text{N}$ and $8.0\,\text{N}$.Since the angle between them is $90^\circ$, the resultant vector $R$ forms the hypotenuse of a right-angled triangle.Thus, $R^2 = P^2 + Q^2$.Substitute $P = 6$ and $Q = 8$:$$R^2 = 6^2 + 8^2 = 36 + 64 = 100$$Taking the square root:$$R = \sqrt{100} = 10.0\,\text{N}$$Answer:The value of the resultant vector is $10.0\,\text{N}$, that is option B.