Question

If $\overrightarrow{a}$ is vector of magnitude $x$ , $m$ is non-zero scalar and $m\overrightarrow{a}$ is a unit vector then x in terms of m is:

• A. $m=x$
• B. $x=\left|m\right|$
• C. $x=\frac{1}{\left|m\right|}$
• D. $x=m/2$

Answer 1

Answer: (C)

$x=\frac{1}{\left|m\right|}$

Given $|m\overrightarrow{a}|=1$

$\Rightarrow |m||\overrightarrow{a}|=1$

$\Rightarrow |m|x=1$

$\Rightarrow x=\frac{1}{|m|}$

Remember: modulus can never be negative