Question

A scientist has developed a system which goes from P to Q by two different paths. Heat given to the system in path 1 is 1000 J. The work done by the system along path 1 is more than path 2 by 100 J. What is the heat exchanged by the system in path 2?

Answer 1

For path 1:

Heat given Q₁ = + 1000 J

Work done = W₁(let)

For path 2:

Work done (W₂) = (W₁ − 100) J

Heat given Q₂ = ?

As change in internal energy between two states for different paths is same.

∴ ∆U = Q₁ − W₁ = Q₂ − W₂

1000 – W₁ = Q₂ − (W₁ − 100)

or  Q₂ = (1000 – 100) J

= 900 J