NEET-XII-Physics
13: Fluid Mechanics
- #10A barometer kept in an elevator accelerating upward reads 76 cm. The air pressure in the elevator is
(a) 76 cm
(b) < 76 cm
(c) > 76 cm
(d) zerodigAnsr: cAns : (c) > 76 cm
When the elevator is going upwards with acceleration a, the effective acceleration is a' = (g + a).
Thus, pressure is given by
`` P=h\,\mathrm{\,\rho \,}\mathit{(}g\mathit{+}a\mathit{)}``
Air pressure in the elevator = `` P=h\text{'}\,\mathrm{\,\rho \,}g``
Because the pressure is the same, h' > h.
∴ Air pressure > 76 cm
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