JEE Mains · Physics · STD 11 - Vectors
- JEE Mains 2020
- Medium
- Numerical
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
Pick an option to check your answer.
Answer & Solution
Correct Answer
(B) \(90\)
Step-by-step Solution
Detailed explanation
\(|\overrightarrow{ P }+\overrightarrow{ Q }|=|\overrightarrow{ P }|\)
\(P ^2+ Q ^2+2 PQ \cos \theta= P ^2\)
\(= Q +2 P \cos \theta=0\)
\(\cos \theta=\frac{- Q }{2 P }\)
\(\tan \alpha=\frac{2 P \sin \theta}{2 P \cos \theta+Q}=\infty\) \([2 P \cos \theta+Q=0]\)
\(\alpha=90^{\circ}\)
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