Both work and heat are path functions . This means the amount of energy transferred depends on how the system got from state A to state B, not just the starting and ending points.

This equation tells us that the energy stored in a system changes only if we add/remove heat or perform work. 3. Modes of Heat Transfer

The work necessary to push a fluid into or out of a control volume (essential for open-system analysis). 5. Key Differences: Heat vs. Work

Engineering thermodynamics classifies heat transfer into three distinct mechanisms:

Heat is released by fuel combustion, which the system then converts into boundary work to move the vehicle.