Q 11-06-131JEE MainJEE Main 2022 (25 Jun, Shift 1)Easy
If force $\vec F = 3\hat i + 4\hat j - 2\hat k$ acts on a particle having position vector $2\hat i + \hat j + 2\hat k$, then the torque about the origin will be:
Answer: (A) $-10\hat i + 10\hat j + 5\hat k$
$$\vec\tau = \vec r\times\vec F = \begin{vmatrix}\hat i & \hat j & \hat k\\ 2 & 1 & 2\\ 3 & 4 & -2\end{vmatrix} = \hat i(-2-8) - \hat j(-4-6) + \hat k(8-3) = -10\hat i + 10\hat j + 5\hat k$$
Solution by Sreeraj P, M.Sc Physics