Problem $5(10$ pts$)$

The situation presented below refers to a particular day at an altitude above standard sea level.

A piston$-$cylinder device with a cross$-$sectional area of $0\mathrm{.}5m^2$ is exposed to a local ambient

pressure $P_{\text{a}\text{t}\text{m}}=96$kPa. The piston of mass equal $30$

kg rests on a base ring support and inside the

cylinder there is water vapor. You are asked to draw

a free body diagram for the piston and determine

the minimum water vapor pressure, in bar, required

to lift the piston. Consider that the acceleration of

gravity is $9\mathrm{.}81\frac{m}{s^2}$ and neglect the friction between

the piston and the cylinder wall. Hint: focus on the

reaction of the base ring support on the piston

before and after the instant when the piston is lifted

by the water pressure.