Question

A $0.2\text{kg}$ object at rest is subjected to a force $(0.3\hat{i}-0.4\hat{j})\text{N}$. What is the velocity of the object (in $m/s$) after $6\text{s}$

• A. $(9\hat{i}-12\hat{j})$
• B. $(8\hat{i}-16\hat{j})$
• C. $(12\hat{i}-9\hat{j})$
• D. $(16\hat{i}-8\hat{j})$

Answer 1

The correct option is A $(9\hat{i}-12\hat{j})$

Here, $m=0.2\text{kg},u=0$ (initial velocity);
$\overrightarrow{F}=(0.3\hat{i}-0.4\hat{j})$ (Given)
$\overrightarrow{a}=\frac{\overrightarrow{F}}{m}=\frac{(0.3\hat{i}-0.4\hat{j})}{0.2}=(\frac{3}{2}\hat{i}-2\hat{j})$
We know, $\overrightarrow{v}=\overrightarrow{u}+\overrightarrow{a}t$
$⟹\overrightarrow{v}=0+(\frac{3}{2}\hat{i}-2\hat{j})\times 6=9\hat{i}-12\hat{j}$