Units, Dimensions & Errors · JEE Main previous year questions

2017 2 questions

1. Q312017 · 9 Apr 2017 · Shift 1

   A physical quantity P is described by the relation $\mathrm{P}={\mathrm{a}}^{1/2}{\mathrm{b}}^2{\mathrm{c}}^3{\mathrm{d}}^{-4}$ If the relative errors in the measurement of a, b, c and d respectively, are 2%, 1%, 3% and 5%, then the relative error in P will be :

   1. A.$8\%$
   2. B.$12\%$
   3. C.$32\%$
   4. D.$25\%$
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   Answer: C

2. Q312017 · 8 Apr 2017 · Shift 1

   Time (T), velocity (C) and angular momentum (h) are chosen as fundamentalquantities instead of mass, length and time. In terms of these, the dimensions of mass would be :

   1. A.$[\mathrm{M}]=[{\mathrm{T}}^{-1}{\mathrm{C}}^{-2}\mathrm{h}]$
   2. B.$[\mathrm{M}]=[{\mathrm{T}}^{-1}{\mathrm{C}}^2\mathrm{h}]$
   3. C.$[\mathrm{M}]=[{\mathrm{T}}^{-1}{\mathrm{C}}^{-2}{\mathrm{h}}^{-1}]$
   4. D.$[\mathrm{M}]=[\mathrm{T}{\mathrm{C}}^{-2}\mathrm{h}]$
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   Answer: A