A Barometer kept in an elevator reads 760 mm when the elevator is at r

A Barometer kept in an elevator reads 760 mm when the elevator is at rest. When the elevator moves in the upward direction with increasing speed, the reading of the Barometer will be:

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760 mm

> 760 mm

Zero

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC CAPF – 2016

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When the elevator moves upward with increasing speed (i.e., it is accelerating upwards), the apparent weight of objects inside the elevator increases. A barometer measures the pressure exerted by the column of air above it. In the upward accelerating frame of reference, the effective acceleration of gravity is (g + a), where g is the standard acceleration due to gravity and a is the upward acceleration of the elevator. The pressure exerted by the air column is proportional to this effective gravity. Therefore, the air pressure measured by the barometer will be higher than the normal atmospheric pressure (760 mm Hg) measured when the elevator is at rest.

This question tests the understanding of apparent weight and pressure measurement in accelerating reference frames.

If the elevator were moving downwards with increasing speed (accelerating downwards), the apparent weight and measured pressure would decrease (reading < 760 mm). If the elevator were moving at a constant velocity (up or down), the acceleration would be zero, and the reading would remain 760 mm. If the elevator were falling freely (a = -g), the apparent weight and pressure would be zero.

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