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
$(5{)}^2=Q_x^2+4^2$
$\Rightarrow Q_x=\sqrt{9}=3$