A frictionless

PHYSICS · Single correct · AP · Physics 1: Algebra-based · Fluids · Fluids

Problem

A frictionless, airtight piston of area

0.010\,\text{m}^2

exerts a downward force of

100\,\text{N}

on the top surface of a

0.20\,\text{m}

layer of oil (density

800\,\text{kg/m}^3

) that floats on a

0.40\,\text{m}

layer of water (density

1000\,\text{kg/m}^3

) in a vertical cylinder. Neglect atmospheric pressure outside the piston. What is the gauge pressure at the oil–water interface? (a)

1.0\times10^{4}\,\text{Pa}

(b)

8.4\times10^{3}\,\text{Pa}

(c)

1.55\times10^{4}\,\text{Pa}

(d)

1.2\times10^{4}\,\text{Pa}