A force (F) = -5i - 7j + 3k acting on a particle causes a displacement (s) = 3i - 2j + ak in its own direction. If the work done is 14 J, then the value of ' a ' is (a) 0 (b) 5 (c) 15 (d) 1

Answer: (b). W = F = (-5)(3) + (-7)(-2) + 3a 14 = -15 + 14 + 3a ⇒ 3a = 15 So the answer is (b) a = 5.

A force (F) = -5i - 7j + 3k acting on a particle causes a… | MHT CET 2019 (2 May, Shift 2)

Q16MHT CET 2019 · 2 MAY · SHIFT 2Easy

Work by a Constant Force

A force $(F) = -5\hat{\mathbf{i}} - 7\hat{\mathbf{j}} + 3\hat{\mathbf{k}}$ acting on a particle causes a displacement $(s) = 3\hat{\mathbf{i}} - 2\hat{\mathbf{j}} + a\hat{\mathbf{k}}$ in its own direction. If the work done is 14 J, then the value of ' $a$ ' is

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Answer: (b)

$W = \vec{F}\cdot\vec{s} = (-5)(3) + (-7)(-2) + 3a$
$14 = -15 + 14 + 3a \Rightarrow 3a = 15$
So the answer is (b) $a = 5$ .

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Work by a Constant Force question from MHT CET 2019 (2 May, Shift 2)

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