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⚡ Physics

Thermodynamics

Thermodynamics deals with heat, temperature, and energy transformations. This module covers heat transfer, calorimetry, gas laws, the laws of thermodynamics, engines, and entropy.

🎯What the Exam Tests

Thermodynamics is 15–20% of the CSCA Physics exam. Most tested: calorimetry, ideal gas law, First Law, Carnot efficiency, PV diagram work.

Temperature Scales

Temperature measures the average kinetic energy of particles. Three scales: Celsius, Fahrenheit, and Kelvin. Convert: T(K) = T(°C) + 273.15. Gas law problems always use Kelvin.

Thermal Expansion

Linear expansion: ΔL = αL₀ΔT. Volume expansion: ΔV = βV₀ΔT, where β ≈ 3α.

Conduction

Q/t = kAΔT/L, where k is thermal conductivity.

Convection

Heat transfer by fluid movement. Warm fluid rises, cool sinks.

Radiation

P = εσAT⁴, Stefan-Boltzmann law. σ = 5.67×10⁻⁸ W/(m²·K⁴).

💡T(K) = T(°C) + 273.15; three heat transfer modes: conduction, convection, radiation.

📋 Key Formulas

  • T(K) = T(°C) + 273.15
  • Q/t = kAΔT/L
  • P = εσAT⁴
  • ΔL = αL₀ΔT

📝 Worked Example 1

Example 1: Steel rod (α=12×10⁻⁶, L=2 m) heated 100°C. ΔL = 12×10⁻⁶ × 2 × 100 = 2.4 mm

📝 Worked Example 2

Example 2: Window: k=0.8, A=2 m², L=5 mm, ΔT=20°C. Q/t = 0.8×2×20/0.005 = 6400 W

📝 Worked Example 3

Example 3: Sphere (ε=1, r=0.1 m) at 500 K. P = 5.67×10⁻⁸ × 0.1257 × 500⁴ = 446 W

🧠Always convert to Kelvin for radiation and gas laws.

🧠Radiation power ∝ T⁴.

🧠Thicker walls reduce conduction.

⚠️Confusing heat and temperature.

⚠️Forgetting °C to K conversion.

⚠️Ignoring water anomalous expansion near 4°C.

🎯 Try This Yourself

Aluminum rod (α=23×10⁻⁶, L=1.5 m) heated 80°C. Expansion?

Module Summary

You have completed Thermodynamics! Key topics: heat transfer, calorimetry, gas laws, PV diagrams, thermodynamic laws, entropy, engines, phase changes, and kinetic theory.

Open and read all sections to complete this module