Physics

Physics

Problem

A jar contains two immiscible liquids: an upper layer of oil 20 cm20\,\text{cm} deep (density 800 kg m−3800\,\text{kg\,m}^{-3}) and a lower layer of water 30 cm30\,\text{cm} deep (density 1000 kg m−31000\,\text{kg\,m}^{-3}). Find the gauge pressure at the bottom of the jar.
Intuitive explanation

Gauge pressure measures how much pressure the fluid adds above atmospheric pressure. Since the liquids are immiscible, each layer contributes independently to the total pressure at the bottom—you just add up the weight of both columns. The key is using P=ρghP = \rho g h for each layer and summing them, remembering that the denser liquid's contribution depends on its own depth, not the total depth.

Intuitive explanation

Gauge pressure measures how much pressure the fluid adds above atmospheric pressure. Since the liquids are immiscible, each layer contributes independently to the total pressure at the bottom—you just add up the weight of both columns. The key is using P=ρghP = \rho g h for each layer and summing them, remembering that the denser liquid's contribution depends on its own depth, not the total depth.

Browse the problem library