Question

A particle is moving eastwards with a velocity $5{\text{ms}}^{-1}$. In $10\text{s}$, the velocity changes to $5{\text{ms}}^{-1}$ northwards. The average acceleration in this time is

• A. $\frac{1}{\sqrt{2}}{\text{ms}}^{-2}NE$
• B. $\frac{1}{2}{\text{ms}}^{-2}N$
• C. Zero
• D. $\frac{1}{\sqrt{2}}{\text{ms}}^{-2}NW$

Answer 1

The correct option is D $\frac{1}{\sqrt{2}}{\text{ms}}^{-2}NW$

$a_{av}=\frac{v_f-v_i}{t}=\frac{5\hat{j}-5\hat{i}}{10}$
$=a=\frac{1}{\sqrt{2}}{\text{ms}}^{-2}\text{NW}$