Mathematical and Physical Journal
for High Schools
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# Problem P. 4640. (May 2014)

P. 4640. The internal energy of an ideal gas is the sum of the kinetic energies of the randomly moving molecules of the gas. The change in the internal energy of the gas is indicated by the change of the temperature of the gas. When the gas is given some energy in an ordered way, then it is called work, and if the energy is given in a disordered way then it is called thermal energy transfer. Which characteristics (states) of the ideal gas, the mass of which is kept constant, remain the same

$\displaystyle a)$ if only thermal energy is added;

$\displaystyle b)$ if only work is done;

$\displaystyle c)$ if the work done by the gas is continuously the same as the thermal energy added to the gas?

(4 pont)

Deadline expired on June 10, 2014.

Sorry, the solution is available only in Hungarian. Google translation

Megoldásvázlat. $\displaystyle a)$ Az ideális gáz térfogata nem változik.

$\displaystyle b)$ Az ideális gáz entrópiája (a molekuláris szintű rendezetlenség mértéke) változatlan marad.

$\displaystyle c)$ Az ideális gáz hőmérséklete és a belső energiája nem változik.

### Statistics:

 48 students sent a solution. 4 points: Berta Dénes, Csathó Botond, Csernák Tamás, Di Giovanni Márk, Farkas Tamás, Horicsányi Attila, Juhász Péter, Krokos Ádám László, Marosvári Kristóf, Németh 017 András, Pázmán Zalán, Sal Kristóf, Szépfalvi Bálint. 3 points: Bugár 123 Dávid, Demeter Dániel, Dinev Georgi, Fekete Panna, Horváth 974 Bence Attila, Kaposvári Péter, Koch Lilla, Molnár 128 Szilárd, Morvay Bálint, Nagy Zsolt, Németh Flóra Boróka, Radnai Bálint, Seress Dániel, Szilágyi Kristóf, Tanner Martin, Trócsányi Péter, Varju Ákos. 2 points: 11 students. 1 point: 2 students. 0 point: 5 students.

Problems in Physics of KöMaL, May 2014