Yes. You can start learning on Learnr for free. Learnr Pro unlocks higher daily limits and extra features.

Learn Thermodynamics

Understand heat, work and entropy, and why no engine can ever be perfect.

Free to start. Built from a single prompt. No credit card.

Thermodynamics is the physics of energy, heat and temperature, and it explains everything from car engines to refrigerators to why ice melts in a warm room. Four laws do most of the work: temperature equilibrium, conservation of energy, the steady growth of entropy and the unreachable absolute zero. You begin with heat, work and the ideal gas law, then learn to analyze processes on pressure-volume diagrams before tackling engines and entropy. Learnr builds a thermodynamics course to fit your level and teaches it as quick interactive lessons that adapt along the way.

How to learn Thermodynamics, step by step

Separate temperature, heat and internal energy. These three get blurred more than anything else in the subject. Temperature is what a thermometer reads, heat is energy transferred because of a temperature difference, and internal energy is what a system contains. Work specific heat and calorimetry problems to make the distinction concrete.
Master the first law with a fixed sign convention. Write the first law as change in internal energy equals heat added minus work done by the system, and stick with that convention. Physics and chemistry textbooks often use opposite signs for work, so check which one your source uses.
Draw every process on a PV diagram. Use PV = nRT and sketch isothermal, isobaric, isochoric and adiabatic paths. Work done equals the area under the curve, so a closed cycle's net work is the enclosed area. Drawing first prevents most sign errors.
Analyze engines with the Carnot limit. Learn why any heat engine must dump some heat to a cold reservoir, then derive the Carnot efficiency, one minus the cold temperature over the hot temperature, in kelvin. Compare it with a refrigerator's coefficient of performance.
Build two pictures of entropy. Define entropy change as reversible heat divided by temperature, then connect it to Boltzmann's S = k ln W, where W counts microstates. Seeing both views explains why mixing, melting and spreading heat all increase entropy.
Drill process problems a few at a time. Thermodynamics rewards repetition on the same handful of process types. Short daily sets in a Learnr course, with a streak to keep you honest, make the formulas and sign conventions automatic.

What you'll learn

Apply the first law of thermodynamics to track heat, work and internal energy in a process
Use the ideal gas law and pressure-volume diagrams to analyze isothermal, isobaric, isochoric and adiabatic processes
Calculate the maximum efficiency of a heat engine with the Carnot formula
Explain entropy both as heat over temperature and as a count of microstates
Use Gibbs free energy to predict whether a process is spontaneous

What's inside your Thermodynamics course

A sample path Learnr builds for Thermodynamics. Your real course adapts to your goal and level.

1. Temperature, heat and the zeroth law
2. Work, internal energy and the first law
3. Ideal gases and thermodynamic processes
4. Heat engines, refrigerators and the Carnot cycle
5. Entropy and the second law
6. Free energy, phase changes and the third law

How long does it take to learn Thermodynamics?

An introductory treatment at the level of a first-year physics or engineering course takes about 2 to 3 months at 4 to 5 hours a week. Engineering thermodynamics with steam tables, or statistical mechanics, adds another semester each, depending on your calculus background.

What you need before you start

Algebra and comfort with units, plus introductory mechanics covering work and energy. Calculus helps a great deal, since work and entropy changes are integrals along a path.

Common mistakes to avoid

Using Celsius instead of kelvin in gas laws and efficiency formulas, which gives nonsense answers. Convert every temperature to kelvin first.
Mixing sign conventions for work between sources. Pick one convention for the first law, write it at the top of each problem and keep it.
Believing entropy can never decrease anywhere. It can fall in an open system like a freezer, as long as total entropy including the surroundings rises.

How Learnr builds your course

Type your topic

Tell Learnr you want to learn Thermodynamics, or get as specific as you like.

Get a personalized course

Learnr instantly builds a full Thermodynamics course tailored to your goal and skill level.

Learn and level up

Move through bite-sized lessons and interactive practice, earning XP and keeping your streak.

Thermodynamics questions, answered

What are the laws of thermodynamics in simple terms?

The zeroth law says systems in thermal equilibrium share a temperature. The first says energy is conserved. The second says total entropy of an isolated system does not decrease, so heat flows from hot to cold on its own. The third says absolute zero cannot be reached in a finite number of steps.

Is thermodynamics hard?

The math is usually lighter than in electromagnetism, but the concepts are subtle. Most difficulty comes from vague definitions of heat and work, which careful early practice fixes.

How is thermodynamics used in chemistry?

Chemists use enthalpy, entropy and Gibbs free energy to predict whether reactions happen, where equilibrium lies and how much energy is released. That branch is covered in physical chemistry.