Question

Resultant of two vectors $\overset{\rightarrow}{A}$ and $\overset{\rightarrow}{B}$is $\overset{\rightarrow}{R}$. Now magnitude of vector is doubled keeping direction same, then magnitude of the resultant becomes |$\overset{\rightarrow}{B}$|. Angle between vector $\overset{\rightarrow}{A}$ and $\overset{\rightarrow}{B}$ is 120ŗ. Then magnitude of $\overset{\rightarrow}{A}$ is equal to –

• A. |$\overset{\rightarrow}{B}$|
• B. 2|$\overset{\rightarrow}{B}$|
• C. $\frac{|\overset{\rightarrow}{B}|}{2}$
• D. 4 |$\overset{\rightarrow}{B}$|

Answer 1

Answer: (C)

$\frac{|\overset{\rightarrow}{B}|}{2}$

Answer 2

2|$\overset{\rightarrow}{A}$| = |$\overset{\rightarrow}{B}$|

|$\overset{\rightarrow}{A}$| = $\frac{|\overset{\rightarrow}{B}|}{2}$