A mercury barometer reads 76 cm in a stationary laboratory. It is then placed in an elevator accelerating vertically upward with 2 m/s². Assuming atmospheric pressure remains unchanged, what will be the new barometer reading? Take g = 10 m/s².
Options

Question

A mercury barometer reads 76 cm in a stationary laboratory. It is then placed in an elevator accelerating vertically upward with 2 m/s². Assuming atmospheric pressure remains unchanged, what will be the new barometer reading? Take g = 10 m/s².

Options

G1 Physics · Accepted Answer

In the stationary laboratory, P(atm) = ρ(Hg)g h₀, where h₀ = 76 cm. In an elevator accelerating upward, g(eff) = g+a = 12 m/s². Atmospheric pressure is unchanged, so ρ(Hg)g h₀ = ρ(Hg)g(eff)h. Cancel ρ(Hg): h = gh₀/g(eff) = 10×76/12 ≈ 63.3 cm. Correct option: C.