JEE Main & Advanced
Mathematics
Vector Algebra
Question Bank
Critical Thinking
question_answer
The moment about the point \[M(-2,\,4,\,-6)\] of the force represented in magnitude and position by \[\overrightarrow{AB}\] where the points A and B have the co-ordinates \[(1,\,2,\,-3)\] and \[(3,\,-4,\,2)\] respectively, is [MP PET 2000]
A)8i - 9j - 14k
B)2i - 6j + 5k
C)- 3i + 2j - 3k
D)- 5i + 8j - 8k
Correct Answer:
A
Solution :
Force \[\mathbf{F}=\overrightarrow{AB}=\left( 3-1 \right)\,i+\left( -4-2 \right)\,j+\left( 2+3 \right)\,k\]
\[=2i-6j+5k\]
Moment of Force \[\overrightarrow{F}\] w.r.t \[M=\overrightarrow{MA}\times \overrightarrow{F}\]