= p0, where p0 is just the atmospheric pressure. IDEAL GAS LAW
Consider a column of air sealed inside a syringe and plunger apparatus. Set the plunger at about the 20 cm mark, and designate the enclosed volume of gas by V0. In the absence of an applied force F, the gauge pressure pg is zero, and the absolute (total) pressure p = 1 atm = 106 = p0, where p0 is just the atmospheric pressure.
If the air column behaves as an ideal gas, it should obey pV = Nkt.
But since p = pg + p0 = 
+ p0, an ideal gas should also obey F a V-1.
1) by varying the applied force F (F could be positive or negative), vary the volume V. Plot F vs V-1, construct the best fitting straight line. (Be sure that you have F in one direction as positive & F in the other direction as negative. You should have 1 straight line, not 1 wiggely line or 2 lines!!!!!)
2) Dismiss any applied force & let p & V return to p0 and V0. Assuming the air to be an ideal gas, calculate the number of molecules N in your sample (or moles if you prefer). (Note the temperature in the lab)
3) Using the kinetic theory result for the internal energy for ideal gases, calculate the internal energy of your sample.
U = 
NkT = p0V0. (Be sure to convert your units!)
Last Updated: 4 Jan 2001