Question

A truck traveling due north at $20m/s$ turns west and travels
at the same speed. What is the change in the velocity?

• A. $40m/sNW$
• B. $40m/sSW$
• C. $20\sqrt{2}m/sNW$
• D. $20\sqrt{2}m/sSW$

Answer 1

The correct option is D $20\sqrt{2}m/sSW$

From figure
${\overrightarrow{v}}_1=20\hat{j}$ and ${\overrightarrow{v}}_2=-20\hat{i}$
$\Delta \overrightarrow{v}={\overrightarrow{v}}_2-{\overrightarrow{v}}_1=-20(\hat{i}+\hat{j})$
$|\Delta \overrightarrow{v}|=20\sqrt{2}$ and direction
$\theta ={\tan }^{-1}\left(1\right)={45}^o$ i.e. S-W