Specific Heat and Calorimetry

Every substance stores heat differently. Specific heat capacity (c) is the energy required to raise 1 kg of a material by 1 kelvin, and the heat needed for a given temperature change is Q = m·c·ΔT. This single equation powers cooking, engine cooling, HVAC design, and climate science.

Why Water Is Special

Water's capacity of 4,186 J/(kg·K) is the highest of common substances. It takes 4.6 times more energy to heat water than the same mass of iron. This is why water is the default coolant everywhere from car engines to nuclear plants, and why large bodies of water smooth out seasonal temperature swings.

Measuring Heat in Practice

Engineers measure heating in kilojoules or kilowatt-hours (1 kWh = 3.6 MJ). Heating 200 L of water from 15 °C to 60 °C needs 200 × 4186 × 45 = 37.7 MJ ≈ 10.5 kWh — the dominant energy cost of an electric water heater, and the reason tank insulation pays for itself.