QJEEM20Phf009: JEE Main 2020 Physics - Class 11 JEEM20Phf009 Solution: The sum of two forces and is such that . The angle (in degrees) …

Step-by-Step Verified Solution

$\overrightarrow P + \overrightarrow Q = \overrightarrow R$

$\Rightarrow$ P² + Q² + 2PQcos $\theta$ = R² = P²

[As $\left| {\overrightarrow R } \right| = \left| {\overrightarrow P } \right|$ ]

$\Rightarrow$ 2Pcos $\theta$ + Q = 0

tan $\alpha$ = ${{2P\sin \theta } \over {Q + 2P\cos \theta }}$ = $\infty$

$\Rightarrow$ $\alpha$ = 90^o