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Fluid Mechanics — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsFluid Mechanics1 Mark
MCQ
A barometer kept in a stationary elevator reads $76 cm$. If the elevator starts accelerating up the reading will be
  • A
    Zero
  • B
    Equal to $76 cm$
  • C
    More than $76 cm$
  • ✓
    Less than $76 cm$
✓

Answer

Correct option: D.
Less than $76 cm$
(d)
$h=\frac{P}{\rho g} $
$ \therefore h \propto \frac{1}{g}$. If lift moves upward with some acceleration then effective $g$ increases. So the value of $h$ decreases i.e.reading will be less than $76 \mathrm{~cm}$.

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