The internal energy of the system of bodies was equal to U Q = 500 J. The system did the work of 200 J

The internal energy of the system of bodies was equal to U Q = 500 J. The system did the work of 200 J, and then 1 kJ was done on it. Write down the expression for the change in internal energy and determine the final internal energy of the UK system.

Given:

1) U1 = 500 J.

2) A1 = -200 J.

3) Аz = 1 kJ = 1,000 J.

Find: Uz =?

Solution :

1 action) ΔU = U₂ – U₁ -?

2 action) U₂ = U₁ + A₁ + A₂ = 500 J – 200 J + 1000 J = 1300 J.

3 action) ΔU = 1,300 J – 500 J = 800 J.

Answer: 8 0 0 J.