Question

The gas is cooled such that it looses $65J$ of heat. The gas contracts as it cools and work done on the system equal to $20J$ is exchanged with the surroundings. What are q, w and E?

Answer 1

We know that,

When Heat released has negative sign

So,

$q=-65J$

And work done on the system has positive sign

So,

$w=+20J$

Now the expression for the change in the internal energy is

$\Delta E=-65+20=-45J$

Hence,

$q=-65J,w=+20J,\Delta E=-45J$