Pressure, constant volume gas thermometer, and thermodynamics

[nibbles198]

Just a note before I start off, this was the first line on this homework assignment:

"If you have not studied this yet you can do this problem after reading about it in your textbook."...

I've honestly tried reading about this stuff, but our teacher hasn't even started thermodynamics yet (our midterm on mechanics was yesterday, and this is due tomorrow). I'm genuinely confused, could anyone help teach me some of this?

Here are the problems:


PROBLEM ONE: A U-tube stands vertically and has fluid in it and the pressure
on the left side on the surface of the fluid is P and the pressure on the other side is 3P . The
acceleration of gravity is g . The density of the fluid is •
. The cross sectional area of the tube is

A . Calculate the difference in height of the two surfaces in terms of quantities given or a subset
thereof.

PROBLEM TWO: This problem concerns a constant volume gas thermometer.
Using the Celsius scale for temperature sketch P vs T for three different gases in a constant
volume gas thermometer. The gases are hydrogen , helium and neon. Be sure to label which gas
is which in the sketch. Label the intercept of the horizontal ( Temperature ) axis. What is special
about that point?

PROBLEM THREE: A block of ice of mass M is at a temperature – 40o
Celsius and is taken out of the extremely cold freezer and placed in an oven that provides heat to
the ice at a constant rate in X joules per second. The temperature of the ice rises and eventually
the ice turns into gaseous water. Sketch Temperature vs time for this experiment where time = 0
when you first put the ice into the oven . Label important quantities on the sketch like the slopes
of lines and relevant times. The specific heat of solid, liquid , and gaseous H2 O is CS CLCG .
the latent heats of fusion and vaporization for H2 O are Lf and Lv .

Thank you so much for your help in advance. I want to learn thermodynamics, and I'm interested in it, but giving us a homework on a chapter that we haven't even talked about seems rediculous to me.

 

[Andrew Mason]

Problem #1 is simply an application of Newton's laws: Force (= Pressure x Area) = ma. If the levels remain constant is the water moving? So what does that tell you about the forces on the water? What force other than the forces provided by the gas pressures has to be taken into account.

The others require more information and some understanding of heat capacities.

AM