Question

A 50-cm-thick layer of oil floats on a 120-cm-thick layer of water. What is the pressure at the bottom of the water layer?

Short answer

Total pressure at the bottom of the water is 117 Kpa

Step-by-step solution

Given information

A 50-cm-thick layer of oil floats on a 120-cm-thick layer of water.

Explanation

Total pressure exerted is sum of pressure exerted by oil , water and atmospheric pressure

That means

P_Total = P_o + P_oil+ P_Water

P_o = 101 kPa

P_oil = h_oil ρ_oil g

P_Water = h_Water ρ_Water g

ρ_Water = 1000 kg/m³

ρ_oil = 870 kg/ m³

Now substitute the value and get P_Total

P_Total = 101 kPa + ( 0.5 m x 870 kg/m³ x 9.8 m/s²) + ( 1.2 m x 1000 kg/m³ x 9.8 m/s²)

P_Total = 117 kPa