An impulse of 6m $\vec{j}$ is applied to a body of mass m moving with velocity ($\vec{i} + 2\vec{j}$). The final velocity of the body will be
Answer & explanation
Correct answer: option 3
Impulse = Change in linear momentum
$\vec{\Delta p} = \vec{p_f} - \vec{p_i}$
$\vec{p_f} = \vec{p_i} + \vec{\Delta p} = m\vec{i}+2m\vec{j}+6m\vec{j}$
⇒ m$\vec{v_f} = m\vec{i}+8m\vec{j}$
⇒ $\vec{v_f} = \vec{i}+8\vec{j}$