Practice question

**Modes of energy transfer** work is force times displacement, e.g., gas expansion W = P ΔV, heat is due to temperature gradient, internal energy change same for different combinations of Q and W, e.g., same ΔU can be achieved by adding heat at constant volume or doing work adiabatically, illustrating equivalence but distinction in mechanism. The Zeroth Law states that if two systems are in thermal equilibrium with a third, they are in equilibrium with each other, establishing temperature as a measurable property. It does not involve heat flow direction or work, which are addressed by other laws. Using first law ΔU = Q -