The Fire of Matter

NODE 01

The Thermal World

🧊

vs

🔥

• Ice melts, water boils, metal expands.
• What is changing inside matter?
• Matter contains particles in continuous motion.

NODE 02

Temperature

• Central observable of this realm.
• Thermal state, intensive quantity.
• Temperature is NOT the same thing as heat.

NODE 03

Thermal Equilibrium

• No net heat transfer between systems in contact.
• Temperature equality.

NODE 04

Zeroth Law

A=B

B=C

∴ A = C

• If A is in equilibrium with B, and B with C...
• ...then A is in equilibrium with C.
• Underlies thermometry.

NODE 05

Thermometers

• Thermal expansion, resistance, infrared.
• Calibration, sensitivity, resolution.

NODE 06

Temperature Scales

C

F

K

• Celsius, Fahrenheit, Kelvin.
• K = °C + 273.15
• °F = (9/5)°C + 32

NODE 07

Heat

• Energy transferred because of a temp difference.
• Thermal energy transfer.
• Joule, Calorie. Heat ≠ Temperature.

NODE 08

Heat Capacity (C)

• Heat required to raise temp of a body.
• Q = CΔT.
• Total-body property, depends on mass.

NODE 09

Specific Heat (c)

Q= m cΔT

• For a substance: Q = mcΔT.
• Material dependence.
• Why equal masses heat differently.

NODE 10

Thermal Mass

• Greater heat capacity = requires more energy for same ΔT.
• Water as a thermal reservoir.
• Climate moderation.

NODE 11

Calorimetry

• Quantitative study of heat transfer.
• Heat lost = Heat gained (in isolated system).
• Specific heat determination.

NODE 12

Mixing Problems

• Hot body + Cold body → Equilibrium temp.
• Mass, initial/final temp, specific heat.
• Negligible-loss assumption.

NODE 13

Principle of Calorimetry

• Energy leaving warmer = Energy entering cooler.
• Connects Realm 10 to conservation (Realm 06).

NODE 14

Thermal Expansion

• When temp changes, dimensions change.
• Linear, Area, and Volume expansion.

NODE 15

Linear Expansion

ΔL = α L₀ ΔT

• For small temperature changes.
• Coefficient of linear expansion (α).
• Material dependence.

NODE 16

Area Expansion

• Isotropic materials: ΔA ≈ 2αA₀ΔT.
• Surface expansion, dimensional change.

NODE 17

Volume Expansion

• Isotropic solids: ΔV ≈ 3αV₀ΔT.
• Coefficient of cubical expansion.
• Crucial for liquids.

NODE 18

Expansion Apps

• Railway gaps, bridges, power lines.
• Engineering structures MUST accommodate it.

NODE 19

Bimetallic Strips

• Two bonded metals with different α bend when heated.
• Thermostats, thermal switches.

NODE 20

Anomalous Water

• Max density near 4°C.
• Expands below this temperature.
• Why ice floats and lakes freeze from the surface.

NODE 21

Change of State

• Solid ↔ Liquid ↔ Gas.
• Melting, freezing, vaporization, condensation.
• Sublimation, deposition.

NODE 22

Latent Heat

Q= mL

• Energy transfer without temp change during phase change.
• Q = mL (Fusion, Vaporization).

NODE 23

Melting & Freezing

• Solid ↔ Liquid.
• Supplying energy during melting doesn't raise temp.

NODE 24

Boiling & Cond

• Liquid ↔ Gas (throughout the liquid).
• Pressure dependence, boiling point.

NODE 25

Evaporation

• Occurs at surface, below boiling temp.
• Produces cooling. Depends on Area, Temp, Wind.

NODE 26

Newton's Cooling

• Rate of cooling ∝ temp difference from surroundings.
• Exponential-like approach under ideal conditions.

NODE 27

Heat Transfer

CONDCONVRAD

• Conduction, Convection, Radiation.
• Three fundamental mechanisms.

NODE 28

Conduction

• Transfer without bulk movement of material.
• Particle interactions, temp gradient.
• Metal rod, cooking pan.

NODE 29

Thermal Cond

Q/t = kAΔT/L

• 1D steady conduction through uniform slab.
• k = Thermal conductivity.

NODE 30

Convection

• Transfer involving bulk fluid motion.
• Natural (density diffs) vs Forced (fans).
• Boiling water, atmospheric circulation.

NODE 31

Radiation

• EM radiation. Does NOT require a medium.
• Infrared, emission, absorption, reflection.

NODE 32

Black vs Shiny

• Dark/matte: Good absorbers/emitters.
• Shiny/light: Reflect more, emit/absorb less.

NODE 33

Equilibrium Flow

• Heat transfers until equilibrium is approached.
• HOT → HEAT TRANSFER → COLD.

NODE 34

Heat Engines Pre

• Heat input → useful work + rejected heat.
• Steam engines, internal combustion, turbines.
• Gateway to Thermodynamics.

NODE 35

Refrigeration Pre

• Work input → transfer heat from cold to hot.
• AC, Heat pump. Full analysis in Realm 11.

NODE 36

Thermal Insulation

• Reducing conduction, convection, radiation.
• Trapped air, multi-layer, vacuum.

NODE 37

Thermos Flask

• Minimizes all three transfer mechanisms.
• Insulating materials + Vacuum + Reflective surfaces.

NODE 38

Physics in Nature

🌊☁️🌧️

• Ocean temps, atmospheric heating, clouds.
• Sea breezes, Earth's energy balance.

NODE 39

Physics in Human

• Body temp regulation, sweating, evaporation.
• Heat loss, convection, radiation.

NODE 40

Physics in Tech

❄️⚙️☀️

• Refrigerators, boilers, heat exchangers.
• Computer heat sinks, solar water heaters.

NODE 41

Graph Chamber

• Temp vs Time, Heat vs Temp.
• Heating regions, phase-change plateaus.

NODE 42

Heating Curve

• Solid → Melting → Liquid → Boiling → Gas.
• Temp rises vs energy used for phase change.

NODE 43

Cooling Curve

• Reverse sequence (Gas → Condens → Liq → Freezing).
• Latent heat from the opposite direction.

NODE 44

Exp Experiments

• Metal rod expansion, ball-and-ring.
• Bimetallic strip. Temp → dimension → coefficient.

NODE 45

Calorimetry Lab

• Specific heat, mixing hot/cold water.
• Latent heat, cooling curves.

NODE 46

Heat Transfer Lab

C

C

R

• Compare conductors, observe convection.
• Radiation absorption, insulation effectiveness.

NODE 47

Misconceptions

• "Heat = Temp" → No.
• "Object contains heat" → It has internal energy.
• "Cold flows into hot" → Energy transfers Hot → Cold.

NODE 48

Solving Engine

• System? Initial Temps? Transfer?
• ΔT (mcΔT) or Phase Change (mL)?
• Conduction/Convection/Radiation?

NODE 49

Master Map

MICROSCOPIC MOTION → TEMPHEAT TRANSFER → CALORIMETRYEXPANSION → PHASE CHANGE

• The entire realm compressed.

NODE 50

Deep Connection

• R07 Gravity → Pressure. R08 Solids → Expand.
• R09 Fluids → Convect. R10 Heat → Engines.