1. A system absorbs 1.57E2 kJ of heat and the surroundings do 1.096E2 kJ of work on the system. What is the change in internal energy (in kJ) (ΔU) of the system?

Question

2. The air in an inflated balloon (the system) absorbs 125 J of heat from its proximity to a fire. The balloon expands and does 85 kJ of work. What is the change in internal energy (in kJ) (The air in an inflated balloon (the system) absorbs 125 J of heat from its proximity to a fire. The balloon expands and does 85 kJ of work. What is the change in internal energy (in kJ) (\DeltaU) for the system? Enter only the numerical value.

Answer 1

1. Isn't dU = q + w? So all you need to worry about are the signs on q and w.
2. Same as 1.