Question

A 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) zero.

Answer 1

Answer ⇒  Option (c).

Explanation ⇒ When the elevator is accelerating upward, then Pressure of atmosphere will be equal to,

  P₀ = hρ(g + a)

where h = 76 cm.

Now, At Ordinary conditions pressure of the atmosphere is given by,

P = hρg, h = 76 cm.

Now, we can see P₀  > P, because of g + a.

Thus, P  < 76 cm

Hence, Option (c). is correct.

Hope it helps.