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Question
A barometer kept in an elevator accelerating upward reads 76 cm. The air pressure in the elevator is
Options
76 cm
< 76 cm
> 76 cm
zero
Solution
> 76 cm
When the elevator is going upwards with acceleration a, the effective acceleration is a' =(g + a).
Thus, pressure is given by
P = hρ(g + a)
Air pressure in the elevator = P = h'ρg
Because the pressure is the same, h' > h.
∴ Air pressure > 76 cm
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