Answer:
The amount of work we could expect to get out of the system per second = 28,000J/s
Explanation:
Given the power supplied to the system as 28kW;
Energy = power / time
At very best, the amount of work we could expect to get out of the system per second = 28,000 W / 1 second = 28,000J/s
Therefore, for a a furnace which supplies 28kW of thermal power at 300C to an engine and exhausts waste energy at 20C.
At the very best, the amount of work we could expect to get out of the system per second = 28,000J/s