Thermal Appetite
Specific heat capacity — why water tames climates
What this lesson covers
Why it matters
Noon at the beach: the sand scalds, the sea is mild. Midnight: sand cold, sea still mild. Same sun fed both — one of them just has a bigger thermal appetite.
The idea in plain words
The equation of every heating problem. Tap the terms.
Q = m × c × ΔT
Heat needed to warm 2 kg of water from 25 °C to 75 °C?
Q = 420,000 J = 420 kJ
- joule: Q — heat given or taken
- J/kg°C: c — specific heat capacity — heat to raise 1 kg by 1 °C; water's 4200 J/kg°C is famously huge
- °C: ΔT — the temperature change — what you observe
- why c matters: consequences — water as coolant (radiators), hot-water bottles, mild coastal climates, farmers flooding fields on frost nights
- Q = mcΔT = 2 × 4200 × 50
Predict first
Equal heat to 1 kg each of water, iron and sand. Which gets hottest?
ΔT = Q/mc. Iron's c (0.46) is a ninth of water's (4.2): same joules, nine times the jump.
- Iron — smallest specific heat capacity, biggest temperature jump — correct
- Water — it boils, after all
- All equal — equal heat, equal rise
What you do
Predict the winner, then fire equal heat into all three and watch the thermometers race.
Check yourself
Water is used in car radiators because…
Per kilogram, water swallows more heat than almost anything — the engine's bodyguard.
Coastal cities have milder summers and winters than inland deserts because…
The ocean is a thermal flywheel: slow to heat, slow to cool — Mumbai vs Delhi in one concept.
5 kg of a metal takes 9200 J to rise 4 °C. Its c is…
c = Q/(mΔT) = 9200 ÷ (5×4) = 460 — identifying metals by their thermal appetite.
- its high c lets it soak up lots of heat with little temperature rise — correct
- it is cheap only
- it boils away the heat
- the sea's huge thermal capacity resists temperature swings — correct
- sea breezes are magic
- salt lowers temperatures
- 460 J/kg°C (iron!) — correct
- 1840 J/kg°C
- 46 J/kg°C