Mathematical and Physical Journal
for High Schools
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# Problem P. 4365. (September 2011)

P. 4365. In a container there is a sample of air at a pressure of 5.105 Pa, and at a temperature of 350 K. The air is compressed at constant pressure to 4/5 of its original volume, while a 1000 J work is done.

a) What will the temperature of the air be?

b) What is the change in the internal energy of the sample of air?

c) What is the density of the compressed air?

(4 pont)

Deadline expired on October 10, 2011.

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

Megoldás. $\displaystyle a)$ $\displaystyle T=\frac{4}{5}T_{0}=280~$K.

$\displaystyle b)$ A belső energia 2500 J-lal csökken.

$\displaystyle c)$ $\displaystyle 6{,}2~\frac{\rm kg}{\rm m^3}.$

### Statistics:

 129 students sent a solution. 4 points: 64 students. 3 points: 33 students. 2 points: 14 students. 1 point: 18 students.

Problems in Physics of KöMaL, September 2011