OnlineCBT
Physics · MOTION IN A PLANE
हिन्दीTwo vectors \( \mathbf{A} \) and \( \mathbf{B} \) have magnitudes of \( 5\text{ units} \) and \( 12\text{ units} \) respectively. If the magnitude of their resultant \( \mathbf{R} = \mathbf{A} + \mathbf{B} \) is \( 13\text{ units} \), the angle \( \theta \) between \( \mathbf{A} \) and \( \mathbf{B} \) is:
Correct answer · Option 2
\( 90^\circ \)
Explanation
\( R^2 = A^2 + B^2 + 2AB\cos\theta \Rightarrow 13^2 = 5^2 + 12^2 + 2(5)(12)\cos\theta \Rightarrow 169 = 169 + 120\cos\theta \Rightarrow \cos\theta = 0 \Rightarrow \theta = 90^\circ \).
