Question

A volume of 20 cu ft of air at a pressure of 50 psig is heated and expanded to 30 cu ft and 40 psig. Find the change in the energy of air in joules.

Answer 1

To find the change in the energy of air in joules, you need to calculate the work done by the system and subtract it from the heat added to the system.

Step-by-step explanation:

The change in the energy of air can be calculated using the first law of thermodynamics, which states that the change in energy of a system is equal to the heat added to the system minus the work done by the system. In this case, the heat added to the system is given as 117 J and the work done by the system can be calculated using the formula:

work = pressure * change in volume

Using the given values of initial volume (20 cu ft), final volume (30 cu ft), initial pressure (50 psig), and final pressure (40 psig), we can calculate the change in volume and then the work done by the system. Finally, we can calculate the change in energy by subtracting the work done from the heat added.