JEE Mains · Physics · STD 11 - 3.1 vectors
Two forces \(P\) and \(Q\), of magnitude \(2F\) and \(3F\), respectively, are at an angle \(\theta \) with each other. If the force \(Q\) is doubled, then their resultant also gets doubled. Then, the angle \(\theta \) is ....... \(^o\)
- A \(120\)
- B \(60\)
- C \(90\)
- D \(30\)
Answer & Solution
Correct Answer
(A) \(120\)
Step-by-step Solution
Detailed explanation
\(\begin{array}{l} 2\left| {\vec P + \vec Q} \right| = \left| {\vec P + 2\vec Q} \right|\\ \Rightarrow \,13 + 12\,\cos \,\theta = 10 + 6\,\cos \theta \\ \cos = - \frac{1}{2}\\ \theta = {120^ \circ } \end{array}\)
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