Question

A 0.2 kg object at rest is subjected to a force $(0.3\stackrel{\wedge }{i}-0.4\stackrel{\wedge }{j})N$. What is the velocity after 6s?

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

Answer 1

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

Force acting on an object $=\overrightarrow{F}=\frac{d\overrightarrow{p}}{dt}$

$⟹\Delta \overrightarrow{p}={\int }_0^t\overrightarrow{F}dt$

$⟹\overrightarrow{p_f}-0=(0.3\hat{i}-0.4\hat{j})\times 6kgm/s$

$⟹\overrightarrow{v_f}=(9\hat{i}-12\hat{j})N$