Question

A particle has an initial velocity of $3\hat{i}+4\hat{j}$ and an acceleration of $0.4\hat{i}+0.3\hat{j}$. Its speed after $10s$ is:

• A. $10$ units
• B. $7\sqrt{2}$ units
• C. $7$ units
• D. $8.5$ units

Answer 1

The correct option is B $7\sqrt{2}$ units

$\overrightarrow{v}=\overrightarrow{u}+\overrightarrow{a}t$

$\overrightarrow{v}=(3\hat{i}+4\hat{j})+10(0.4\hat{i}+0.3\hat{j})$

$\overrightarrow{v}=7\hat{i}+7\hat{j}$

$|\overrightarrow{v}|=7\sqrt{2}$