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Question: Answered & Verified by Expert
A force $F$ is given $F=a t+b t^2$, where, $t$ is time. What are the dimensions of $a$ and $b$ ?
PhysicsUnits and DimensionsJIPMERJIPMER 2013
Options:
  • A $\left[\mathrm{MLT}^{-1}\right]$ and $\left[\mathrm{MLT}^0\right]$
  • B $\left[\mathrm{MLT}^{-3}\right]$ and $\left[\mathrm{ML}^2 \mathrm{~T}^4\right]$
  • C $\left[\mathrm{MLT}^{-4}\right]$ and $\left[\mathrm{MLT}^1\right]$
  • D $\left[\mathrm{MLT}^{-3}\right]$ and $\left[\mathrm{MLT}^{-4}\right]$
Solution:
1745 Upvotes Verified Answer
The correct answer is: $\left[\mathrm{MLT}^{-3}\right]$ and $\left[\mathrm{MLT}^{-4}\right]$
Force $F=a t+b t^2$
From principle of homogeneity,
Dimension of at $=\frac{[F]}{[t]}=\frac{\left[\mathrm{MLT}^{-2}\right]}{[\mathrm{T}]}$
$=\left[\mathrm{MLT}^{-3}\right]$
Similarly, dimensions of
$b=\frac{[F]}{\left[t^2\right]}=\frac{\left[\mathrm{MLT}^{-2}\right]}{\left[\mathrm{T}^2\right]}\left[\mathrm{MLT}^{-4}\right]$

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