Q. 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
A) $\hat i-\hat k$
B) $\hat i+\hat k$
C) $\hat j+\hat k$
D) $\hat i-\hat j+\hat k$
Explanation
[Solution by Dr. Abubacker] $\vec\tau=\vec r\times\vec F=\begin{vmatrix}\hat i&\hat j&\hat k\\1&1&1\\2&1&2\end{vmatrix}=(2-1)\hat i-(2-2)\hat j+(1-2)\hat k=\hat i-\hat k$. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.