P. 4521. A sample of air of volume V1=3 dm3 and of pressure p1=6.104 Pa is confined to a fixed vertical cylinder which is closed at its bottom by a piston of cross section A=1 dm2, which can move frictionlessly. The piston is connected to the closed end of the cylinder with a spring, designed for both compression and tension, of length L0=0.6 m and of spring constant D=1000 N/m. The system is in equilibrium in this position. The external air pressure is p0=105 Pa.
a) Find the mass of the piston.
b) The air in the piston is heated slowly. How much heat must be added to the confined air in order to reach that state when the spring does not exert any force on the piston?
Deadline expired on 10 April 2013.
Google Translation (Sorry, the solution is published in Hungarian only.)
Megoldásvázlat. \(\displaystyle a)\) \(\displaystyle m\approx 10\) kg.
\(\displaystyle b)\) A gáz által végzett munka \(\displaystyle 225~\)J, a belső energia változása \(\displaystyle \Delta E=900~\)J, a közölt hő \(\displaystyle Q=1125~\)J.