Q124 / 160 · AP EAMCET 2023 (18 May Shift 1) · Physics

The resultant magnitude of two vectors of same magnitude is equal to magnitude of either. The angle between the two vectors is

  • A
    $30^{\circ}$
  • B
    $60^{\circ}$
  • C
    $90^{\circ}$
  • Correct answer
    D
    $120^{\circ}$

Solution

Resultant of vectors is given by: $\mathrm{R}^2=\mathrm{a}^2+\mathrm{b}^2+2 \mathrm{ab} \cos \theta$ Given $R=a=b=x$ $x^2=x^2+x^2+2 x^2 \cos \theta$ $\begin{aligned} & -\frac{1}{2}=\cos \theta \\ & \theta=120^{\circ}\end{aligned}$

Hence, the correct answer is option: 'D'.

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