- #26

Chestermiller

Mentor

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We know that, at a given location, pressure acts equally in all directions (up, down, left, right). However, pressure can (and does) vary with location.Hmm, So vapor pressure is acting upward?

At a given location, the pressure acts equally in all directions. If half the weight of the water is now above the liquid/vapor interface, there are two ways of calculating the pressure at the interface.But it still does pressure on the surface because of it is weight??? ( Shouldn't the pressure on the top of the liquid increase? Should This be calculated as the following Mbefore - Mafter = Mvapor then Mg/A? And when it tells me that the pressure of the vapor is for example 10 Pa does that mean that it is acting upward?)

Method 1. Pressure at piston + Mvapor x g/A=10000+5 /0.01 = 10500 Pa

Method 2. Pressure at base of cylinder - Mliquid x g/A = 10500 - 5/0.01=10500 Pa

CorrectSolutions to the question:

1) 11000 N/m^2

Not correct. Pressure at piston is always determined by weight of piston in this problem, and is always equal to 10000 Pa.2) Piston pressure is 100/0.01 which is 10000 N/M^2 + 0.5*10/0.01 = 10500 N/M^2 Or Pa

Summary:

Gas pressure at piston face = 10000 Pa

Gas and liquid pressure at liquid/vapor interface = 10500 Pa

Liquid pressure at base of cylinder = 11000 Pa

So, under these circumstances, when half the liquid has formed vapor, what is the (uniform) temperature in the system?