Question

Some gas at 300K is enclosed in a container. Now the container is moving in a fast moving train. While the train is in motion the temperature of the gas:
a) rises above 300K
b) falls below 300K
c) remains 300K
d) is uncertain

Answer 1

Hint: In the above question we are basically asked whether the temperature of the gas increases when it is kept in a fast moving train. It is to be noted that the temperature of the gas increases when there is too much randomness among all the molecules of the gas. First we will see how the container kept in such a train is affected and accordingly choose the correct alternatives from those provided.

Complete step by step answer:
It is given to us that the gas is kept in a container such that its thermal equilibrium temperature is 300K. Now further it is placed in a fast moving train. Let us say the train basically moves in one direction. As a result all the molecules will try to fall back in the container. In such a process the molecules of the gas don’t randomly move in the container. If such a phenomena had to happen the molecules would have processed greater kinetic energy and the temperature of the gas in the container would have increased. Therefore from the above data we can conclude that the temperature of the gas will remain constant.

So, the correct answer is “Option c”.

Note: The above scenario can be better understood by considering the following analogy. Let us say there is gas in the container. Let us say one shakes the container rapidly. As a result the randomness inside the container would increase, the molecules will possess greater kinetic energy and as a result the temperature of the gas will increase. Now in the second case, let us say one runs with the speed of the train holding the container of the gas in his hands. As a result the molecules are just moving in one direction. If there is no randomness we can conclude that there will be no rise in temperature.