A body moves from a position r 1 = 2 i ^ - 3 j ^ - 4 k ^ to a position, r 2 = 3 i ^ - 4 j ^ + 5 k ^ m under the influence of a constant force F = 4 i ^ + j ^ + 6 k ^ N . The work done by the force is

Given, r 1 = 2 i ^ - 3 j ^ - 4 k ^ And r 2 = 3 i ^ - 4 j ^ + 5 k ^ Now, r 2 - r 1 = i ^ - j ^ + 9 k ^ And F = 4 i ^ + j ^ + 6 k ^ ∴ work done = F . r W = 4 i ^ + j ^ + 6 k ^ . i ^ - j ^ + 9 k ^ = 4 - 1 + 54 = 57 J

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PhysicsW.E.P.MiscellaneousEasy2 minPYQ_2020

PhysicsEasysingle choice

A body moves from a position $r_{1} = (2 \hat{i} - 3 \hat{j} - 4 \hat{k})$ to a position, $r_{2} = (3 \hat{i} - 4 \hat{j} + 5 \hat{k})$ m under the influence of a constant force $F = (4 \hat{i} + \hat{j} + 6 \hat{k}) N .$ The work done by the force is

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Answer:

Solution:

Given, $r_{1} = 2 \hat{i} - 3 \hat{j} - 4 \hat{k}$

And $r_{2} = 3 \hat{i} - 4 \hat{j} + 5 \hat{k}$

Now, $r_{2} - r_{1} = \hat{i} - \hat{j} + 9 \hat{k}$

And $F = 4 \hat{i} + \hat{j} + 6 \hat{k}$

$∴$ work done = $F . r$

$W = (4 \hat{i} + \hat{j} + 6 \hat{k}) . (\hat{i} - \hat{j} + 9 \hat{k})$

$= 4 - 1 + 54 = 57 J$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:W.E.P.Subtopic:Miscellaneous

⏱ 2mℹ️ Source: PYQ_2020

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