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

Question

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 (A) 76 cm (B) > 76 cm (C) < 76 cm (D) Zero

Tardigrade Admin · Accepted Answer

When elevator goes up with some acceleration upward, due to pseudo force acting downwards. Value of

g

increases to

g^{'}

.
If

g

increases to

g^{'},

i.e.,

g^{'} = g + a

∵ P = ρ g h = ρ (9 + a) h^{'} =

constant
Then,

h^{'} < h

i.e.,

h^{'} < 76 c m

Q. A barometer kept in an elevator reads 76cm when it is at rest. If the elevator goes up with some acceleration, the reading will be

76 cm

> 76 cm

< 76 cm

Zero

When elevator goes up with some acceleration upward, due to pseudo force acting downwards. Value of g increases to g′. If g increases to g′, i.e., g′=g+a ∵P=ρgh=ρ(9+a)h′= constant Then, h′<h i.e., h′<76cm

Q. A barometer kept in an elevator reads $76 c m$ when it is at rest. If the elevator goes up with some acceleration, the reading will be

When elevator goes up with some acceleration upward, due to pseudo force acting downwards. Value of $g$ increases to $g^{'}$ .
If $g$ increases to $g^{'},$ i.e., $g^{'} = g + a$
$∵ P = ρ g h = ρ (9 + a) h^{'} =$ constant
Then, $h^{'} < h$
i.e., $h^{'} < 76 c m$