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GATE 2022 AG – Question 47

Engineering Mathematics · Vector Calculus · 2 marks · Numerical answer

A particle moves in $\mathbf F=6x^2\hat i+(3xz+y)\hat j+4z\hat k$ along a straight line from(0,0,0) to(1,2,3). Find work as an integer.

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Correct answer: 28 to 28

Explanation

Parameterize $\mathbf r(t)=(t,2t,3t)$, 0≤t≤1. Then $d\mathbf r=(1,2,3)dt$ and $\mathbf F\cdot d\mathbf r=[6t^2+2(9t^2+2t)+36t]dt=(24t^2+40t)dt$. Integrating gives 8+20=**28**. The specified path matters because the field is not conservative.

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