A system does 210 J of work on its environment and gains 80.6 J of heat in the process. Find the change in the internal energy of (a) the system and (b) the environment.

Physics(Please respond) - Elena, Thursday, June 21, 2012 at 2:33am
ÄU = Q - W
Where ÄU is the change in the internal energy of the system,
Q is the heat/energy gained from the surroundings,
W is the work done on the environment.

ÄU =80.6-210=-129.4 J.
The internal energy decreased by 129.4 Joules which corresponds to a temperature decrease of the system

I understand what the internal energy of the system is but I do not understand how to find the environment.

To find the change in the internal energy of the environment, we need to use the law of conservation of energy. According to this law, the total energy change in a system and its surroundings should sum up to zero, as energy cannot be created or destroyed.

Since the system gained 80.6 J of heat, the environment must have lost the same amount of heat, as it was transferred from the environment to the system. Therefore, the change in the internal energy of the environment would be -80.6 J.

This negative sign indicates that the environment lost energy, resulting in a decrease in its internal energy.