Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
Already signed up?
New to KöMaL?
I want the old design back!!! :-)

Problem P. 4479. (November 2012)

P. 4479. An easily moveable, insulated piston, of cross section A=2 dm2 and of mass m=5 kg, confines some air in a vertical thermally insulated cylinder. The air is heated by a heating element of power 200 W.

a) What is the speed of the piston?

b) By what amount does the internal energy of the air change in 2 s?

(5 pont)

Deadline expired on December 10, 2012.

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

Megoldásvázlat. \(\displaystyle a)\) \(\displaystyle v=2{,}8\) cm/s.

\(\displaystyle b)\) 286 J. Ez a fűtőszál által leadott energia 5/7-e, a többi a légkör ,,megemelésére" fordítódik.


130 students sent a solution.
5 points:73 students.
4 points:14 students.
3 points:11 students.
2 points:7 students.
1 point:20 students.
0 point:3 students.
Unfair, not evaluated:2 solutions.

Problems in Physics of KöMaL, November 2012