Question

what is the change in internal energy if 60 j of heat are added to a system and the system does 40 j of work on its surroundings? use u = q - w.

Answer 1

u = q - w

u = 60J - 40J = 20J

Change in internal energy = 20 J.

Answer 2

Answer:

U = 20 J

Explanation:

As per first law of thermodynamics we know that thermal energy given to the system is used to do some work by the system and also it is used to increase the internal energy of the system

So we can say that

$U = Q - W$

here we know that

$Q = 60 J$

also we have

$W = 40 J$

now from above equation we have

$U = 60 - 40 = 20 J$