Respuesta :

mixter17
Hello!

Answer:

1500 J

Explanation:

We are going to use the first law of thermodynamics which can be summarized as:

Δ[tex]U=Q-W[/tex]
[tex]U2-U1=Q-W[/tex]

So, we have that:

[tex]U1=1200j \\ W=400 \\ Q=700j[/tex]

[tex]U2=Q-W+U1[/tex]

By substituting we have:

[tex]U2=700 J - 400 J + 1200J=1500J[/tex] 

Have a nice day :)