A barometer kept in an elevator reads 76 cm when it is at rest. If the elevator goes up with some acceleration, the reading will be ?
The soultion given is like - 
P = dgh = d(g + a)h' = constant
Then, h' < h i.e., h' < 76 cm
Why have they taken pressure as constant ? Won't it change with the change in acceleration ?  

Dear Student,

The pressure you see here in the above equation is the atmospheric pressure which will be same if the elevator is steady or moving upward.
P=density X accleration X height of liquid in barometer.
the pressure measured by the barometer here is the atmospheric pressure, which will be same in both steady and accelerating condition of the elevator.

Hope this helps with your doubt.


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