QJEEM21Ph8062: JEE Main 2021 Physics - Class 11 JEEM21Ph8062 Solution: A force acts on a body of mass 5 kg. If the body starts from…

Question

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A force

\overrightarrow F = (40\widehat i + 10\widehat j)N

acts on a body of mass 5 kg. If the body starts from rest, its position vector

\overrightarrow r

at time t = 10 s, will be :

Accepted Answer

{{d\overrightarrow v } \over {dt}} = \overrightarrow a = {{\overrightarrow F } \over m} = (8\widehat i + 2\widehat j)m/{s^2}

{{d\overrightarrow r } \over {dt}} = \overrightarrow v = (8t\widehat i + 2t\widehat j)m/s

\overrightarrow r = (8\widehat i + 2\widehat j){{{t^2}} \over 2}m

At t = 10 sec

\overrightarrow r = \left[ {(8\widehat i + 2\widehat j)50} \right]m

\Rightarrow \overrightarrow r = (400\widehat i + 100\widehat j)m

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