Question

A sample of gas is placed in an ice bath so that there is 10 J of heat transfer out of the sample. At the same time, the gas is compressed by a piston that does 40 J of Work on the gas. What is the change in thermal energy of the gas

Answer 1

Answer:

$\Delta U=-50J$

Explanation:

Hello,

In this case, we use the equation regarding the first law of thermodynamics which is:

$Q-W=\Delta U$

In this case, the want to compute the change in thermal energy of the gas which is related with ΔU. In such a way, since the 10 J are being removed, they are set as negative in the aforesaid equation, moreover, the 40 J of work are positive since it is a work done on the system. Hence:

$-10J-40J=\Delta U\\\Delta U=-50J$

Best regards.