Q 11-03-014JEE MainAIEEE 2009Easy
A particle has an initial velocity $3\hat{i} + 4\hat{j}$ and an acceleration of $0.4\hat{i} + 0.3\hat{j}$. Its speed after $10$ s is
Answer: (A) $7\sqrt{2}$ units
$$\vec{v} = \vec{u} + \vec{a}t = (3\hat{i} + 4\hat{j}) + (0.4\hat{i} + 0.3\hat{j})(10) = 7\hat{i} + 7\hat{j}$$
$$|\vec{v}| = \sqrt{49 + 49} = 7\sqrt{2}\ \text{units}$$
Solution by Sreeraj P, M.Sc Physics