JEE Mains · Physics · STD 11 - 3.1 vectors
The sum of two forces \(\overrightarrow{\mathrm{P}}\) and \(\overrightarrow{\mathrm{Q}}\) is \(\overrightarrow{\mathrm{R}}\) such that \(|\overrightarrow{\mathrm{R}}|=|\overrightarrow{\mathrm{P}}| .\) The angle \(\theta\) (in degrees) that the resultant of \(2 \overrightarrow{\mathrm{P}}\) and \(\overrightarrow{\mathrm{Q}}\) will make with \(\overrightarrow{\mathrm{Q}}\) is
- A \(80\)
- B \(90\)
- C \(85\)
- D \(95\)
Answer & Solution
Correct Answer
(B) \(90\)
Step-by-step Solution
Detailed explanation
\(|\overrightarrow{ P }+\overrightarrow{ Q }|=|\overrightarrow{ P }|\) \(P ^2+ Q ^2+2 PQ \cos \theta= P ^2\) \(= Q +2 P \cos \theta=0\) \(\cos \theta=\frac{- Q }{2 P }\) \(\tan \alpha=\frac{2 P \sin \theta}{2 P \cos \theta+Q}=\infty\) \([2 P \cos \theta+Q=0]\)…
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