A) \[14\mathbf{i}-8\mathbf{j}+12\mathbf{k}\]
B) \[-14\mathbf{i}-8\mathbf{j}-12\mathbf{k}\]
C) \[7\mathbf{i}+9\mathbf{j}+2\mathbf{k}\]
D) \[7\mathbf{i}-9\mathbf{j}+2\mathbf{k}\]
Correct Answer: D
Solution :
We have, \[\mathbf{F}=\mathbf{i}+\mathbf{j}+\mathbf{k}\] Let\[P(5,\,\,4,\,\,-3)\]and\[O(1,\,\,2,\,\,2)\]be given points. Then, \[OP=4\mathbf{i}+2\mathbf{j}-5\mathbf{k}\] Now, moment of \[\mathbf{F}\] about \[O\] \[=r\times F\left| \begin{matrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 4 & 2 & -5 \\ 1 & 1 & 1 \\ \end{matrix} \right|\] \[=(2+5)\mathbf{i}-(4+5)\mathbf{j}+(4-2)\mathbf{k}\]You need to login to perform this action.
You will be redirected in
3 sec