Question

Magnitude of a vector $Q$ is $5$ and magnitude of its $y$-component is $4$ . So, the magnitude of the $x$-component of this vector is

• A. 8
• B. 3
• C. 6
• D. 9

Answer 1

Answer: (B)

Given, $| Q |=5$
$Q_{y}=4$
$Q_{x}=$ ?
As, $| Q |=\sqrt{Q_{x}^{2}+Q_{y}^{2}}$
$\Rightarrow | Q |^{2}=Q_{x}^{2}+Q_{y}^{2}$
Substituting the given values, we get
$(5)^{2}=Q_{x}^{2}+4^{2}$
$\Rightarrow Q_{x}=\sqrt{9}=3$