Question

A vertical U-tube of uniform inner cross section contains mercury in both sides of its arms. A glycerin (density = 1.3 g/cm³) column of length 10 cm is introduced into one of its arms. Oil of density 0.8 gm/cm³ is poured into the other arm until the upper surfaces of the oil and glycerin are in the same horizontal level. Find the length of the oil column, Density of mercury = 13.6 g/cm³

• A. 10.4 cm
• B. 8.2 cm
• C. 7.2 cm
• D. 9.6 cm

Answer 1

Answer: (D)

9.6 cm

Answer 2

At the condition of equilibrium

Pressure at point A = Pressure at point B

$P_{A} = P_{B}$⇒ $10 \times 1.3 \times g = h \times 0.8 \times g + (10 - h) \times 13.6 \times g$

By solving we get h = 9.7 cm