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Mechanical Engineering QUESTION #2536
Question 1
A force \(\mathbf{F} = 3\hat{i} + 4\hat{j}\) N acts at point \(P(2,\,1,\,0)\) m. The moment vector about the origin is:
  • \(5\hat{k}\) N·m✔️
  • \(-5\hat{k}\) N·m
  • \(8\hat{k}\) N·m
  • \(2\hat{k}\) N·m
Correct Answer Explanation
Moment \(\mathbf{M}=\mathbf{r}\times\mathbf{F}=(2\hat{i}+\hat{j})\times(3\hat{i}+4\hat{j})\). Cross product: \((2\cdot4-1\cdot3)\hat{k}=(8-3)\hat{k}=5\hat{k}\) N·m.