Question

A beaker of height 10 cm is half-filled with water (Sw = 1) and half-filled with oil (So = 1). At what distance (in cm) from the base will the pressure be half the pressure at the base of the beaker?

(a) 4.375

(b) 4.5

(c) 5.5

(d) 5.625

This question was posed to me during an online interview.

I'm obligated to ask this question of Pressure Distribution in a Fluid in section Pressure and Its Measurement of Fluid Mechanics

Answer 1

Correct answer is (b) 4.5

For explanation: Gauge pressure at the base of the beaker = So * 10^3 * 0.05 * g + Sw * 10^3 * 0.05 * g = 882.9Pa. Let the required height be h m from the base.

If 0.05 ≤ h < 0.1,

800(0.1 – h)g = ^1⁄2 * 882.9

Thus, h = 0.04375 (out of the range considered).

If 0 < h ≤ 0:05,

800 * 0.05 * g + 10^3 * (0.05 – h) * g = ^1⁄2 * 882.9

Thus, h = 0.045 (in the range considered). Hence, the correct answer will be 45 cm.