A solid metallic cube of heat capacity S is at temperature 300K. It is brought in contact with a reservoir at 600K. If the heat transfer takes place only between the reservoir and the cube, the entropy change of the universe after reaching the thermal equillibrium is
[Answer : 0.19S]
Q = SΔT
Change in entropy = (change in heat Q)/T
ΔE = Q/T
[I have taken entropy as E rather than usual S since S is already taken for heat capacity]
The Attempt at a Solution
Should I take reservoir as an infinite pool of temperature? Then, I get
Q = SΔT
Q=S*(600-300) since, at thermal equillibrium the temperatures are same
ΔE=(300/600)=0.5 which is not the answer
If I take reservoir which loses temperature, I am unable to continue with the problem since I do not know the heat capacity of it.
Is there a different approach to this problem?