Question

The magnitude of the x-component of vector $\overrightarrow{A}$ is 3 and the magnitude of vector $\overrightarrow{A}$ is 5. What is the magnitude of the y-component of vector $\overrightarrow{A}$?

• A. $3$
• B. $4$
• C. $5$
• D. $8$

Answer 1

Answer: (B)

$4$

$\overrightarrow{A}=A_x\hat{i}+A_y\hat{j}$

Also $A=\sqrt{A_x^2+A_y^2}$

Here $A=5$, $A_x=3$

$\therefore 5=\sqrt{(3{)}^2+A_y^2}$

Squaring both sides we get

$25=9+A_y^2$

$A_y^2=25-9=16$

or $A_y=4$