Final answer:
The change in the balloon air's internal energy can be found by subtracting the work done by the system from the heat added. Given that the heat absorbed is 97.9 J and the work done is 37 J, the internal energy change is 60.9 J.
Step-by-step explanation:
The change in internal energy of the air in a hot air balloon can be calculated using the first law of thermodynamics, which states that the change in the internal energy (ΔU) of a system is equal to the heat (Q) added to the system minus the work (W) done by the system:
ΔU = Q - W
In this case, the hot air balloon absorbs 97.9 J of heat and does 37 J of work. Substituting these values into the formula gives us:
ΔU = 97.9 J - 37 J = 60.9 J
Therefore, the change in the balloon air's internal energy is 60.9 J.