When at rest, a barometer kept inside an elevator shows a reading of 76 cm . If the elevator ascends with increasing speed, the reading will become

Step-by-step solution

When the elevator is at rest, the atmospheric pressure P₀ is balanced by the mercury column of height h₀ = 76 cm . P₀ = g h₀ When the elevator ascends with increasing speed, it moves with an upward acceleration a . The effective acceleration due to gravity inside the elevator becomes g_ eff = g + a . Assuming the atmospheric pressure P₀ remains constant, the new height h of the mercury column is given by: P₀ = g_ eff h = (g + a) h Equating the two expressions for P₀ : g h₀ = (g + a) h h = g g + a h₀ Since g + a > g