Revise: Heat and Temperature
The difference between heat and temperature, specific heat capacity, types of thermometer, temperature scales, and thermal expansion.
Temperature = how hot. Heat = energy transferred due to a temperature difference.
A pool (25°C) holds more heat than a cup of tea (90°C) due to its mass.
Liquid-in-glass (expansion), thermocouple (voltage), infrared (radiation, no contact).
Infrared thermometers check body temperature with no contact.
ΔL = L₀αΔT — most solids expand when heated.
20m steel rail, ΔT=30°C → +7.2mm.
Heat always flows from hot to cold.
A tiny hot spark carries little total heat energy.
c is a fixed material property — water's high c resists temperature change.
5000J raises 1kg by 2°C → c=2500 J/(kg·K).
Choose the thermometer type to match the situation (extreme heat, no contact, etc).
A furnace at 1200°C needs a thermocouple, not liquid-in-glass.
Different materials have different α — this is why bimetallic strips bend when heated.
5m aluminium rod, ΔT=20°C → +2.4mm.