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Question: Answered & Verified by Expert
The motion of a particle along a straight line is described by equation $x=8+12 t-t^3$ where, $x$ is in metre and $t$ in second. The retardation of the particle when its velocity becomes zero, is
PhysicsMotion In One DimensionNEETNEET 2012 (Screening)
Options:
  • A $24 \mathrm{~ms}^{-2}$
  • B zero
  • C $6 \mathrm{~ms}^{-2}$
  • D $12 \mathrm{~ms}^{-2}$
Solution:
2137 Upvotes Verified Answer
The correct answer is: $12 \mathrm{~ms}^{-2}$
Given, $x=8+12 t-t^3$
We know $v=\frac{d x}{d t}$
and $a=\frac{d v}{d t}$
So, $v=12-3 t^2$
and $a=-6 t$
At $t=2 \mathrm{~s}$
$y=0$ and $a=-6 t$
So, $a=-12 \mathrm{~m} / \mathrm{s}^2$
So, retardation of the particle $=12 \mathrm{~m} / \mathrm{s}^2$.

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