What is the First Law of Thermodynamics?

What is the First Law of Thermodynamics?

• A. Energy is neither created nor destroyed.
• B. Energy cannot be converted
• C. Heat flows from hot to cold
• D. Pressure equals temperature times volume

Answer: (A)

Energy cannot be created or destroyed; it can only be transformed from one form to another or transferred between objects. In a building setting, this means the energy you put in—as fuel, electricity, or other sources—will show up elsewhere as heat, light, motion, or stored energy, but the total amount of energy remains the same when you account for all forms and transfers. A handy way to picture this is the internal-energy change: ΔU equals the heat added plus the work done on the system (ΔU = Q + W). This principle underpins how we analyze energy use in MFBO work—fuel energy becomes heat in the space, electrical energy powers equipment that moves energy around, and some energy may be stored as temperature changes or in systems like batteries. The other statements describe different ideas: energy can be converted, heat flow direction is governed by the Second Law, and PV = nRT is a gas law, not a statement of energy conservation.

Energy cannot be created or destroyed; it can only be transformed from one form to another or transferred between objects. In a building setting, this means the energy you put in—as fuel, electricity, or other sources—will show up elsewhere as heat, light, motion, or stored energy, but the total amount of energy remains the same when you account for all forms and transfers. A handy way to picture this is the internal-energy change: ΔU equals the heat added plus the work done on the system (ΔU = Q + W). This principle underpins how we analyze energy use in MFBO work—fuel energy becomes heat in the space, electrical energy powers equipment that moves energy around, and some energy may be stored as temperature changes or in systems like batteries. The other statements describe different ideas: energy can be converted, heat flow direction is governed by the Second Law, and PV = nRT is a gas law, not a statement of energy conservation.