Q 11-04-032NEETJEE MainEasy
The momentum of a particle varies with time as $\vec{p} = (4t^2\,\hat{i} - 3t^2\,\hat{j})$ kg m/s. The magnitude of the force on it at $t = 2$ s is
Answer: (A) $20$ N
$$\vec{F} = \frac{d\vec{p}}{dt} = 8t\,\hat{i} - 6t\,\hat{j}, \qquad |\vec{F}| = 10t$$
At $t = 2$ s: $|\vec{F}| = 20$ N.
Solution by Sreeraj P, M.Sc Physics