A) 15
B) \[3\sqrt{41}\]
C) \[3\sqrt{57}\]
D) None of these
Correct Answer: B
Solution :
\[\mathbf{F}=\overrightarrow{AB}=4\mathbf{i}+4\mathbf{j}-\mathbf{k}\] and \[\overrightarrow{AP}=3\mathbf{i}-3\mathbf{k}\] Moment of the force is \[\overrightarrow{AP}\times \overrightarrow{AB}\] \[=\left| \begin{matrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 3 & 0 & -3 \\ 4 & 4 & -1 \\ \end{matrix} \right|=12\mathbf{i}-9\mathbf{j}+12\mathbf{k}\] \[\therefore \] Magnitude is, \[\sqrt{144+81+144}=3\sqrt{41}.\]You need to login to perform this action.
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