Q 11-06-064JEE MainJEE Main 2025 (22 Jan, Shift 2)Easy
The torque due to the force $(2\hat i + \hat j + 2\hat k)$ about the origin, acting on a particle whose position vector is $(\hat i + \hat j + \hat k)$, would be
Answer: (A) $\hat i - \hat k$
$$\vec\tau = \vec r\times\vec F = \begin{vmatrix}\hat i & \hat j & \hat k\\ 1 & 1 & 1\\ 2 & 1 & 2\end{vmatrix}$$
$$= \hat i(2-1) - \hat j(2-2) + \hat k(1-2) = \hat i - \hat k$$
Solution by Sreeraj P, M.Sc Physics