In an isolated system,

w=0 but

how q=0?

 

Dear user!

To analyze why q = 0 for an isolated system you need to know two things. First, the definition of an isolated system and second is the first law of thermodynamics.

An isolated system can be defined as a type of system which can neither exchange mass nor energy with the surroundings. So, both ∆m and ∆U are equal to zero, where ∆m stands for change in mass and ∆U stands for change in energy. Also, no exchange of energy takes place. So, work done also becomes zero.

Now, recall the equation for the first law of thermodynamics. It is

∆U = q + w

Now, we have already discussed that for an isolated system, ∆U and w are equal to zero.

therefroe, q = 0.

 I hope now the concept of zero heat and zero work for an isolated system is clear.

 All the best!