How to Learn Physics: Understand Concepts, Not Just Formulas

The best way to learn physics is in this order: first understand the concept behind a formula, then practise solving problems, and check every calculation against its units. Anyone who only memorises formulas stalls at the first reworded task; anyone who understands the underlying principles can apply physics even to unfamiliar situations.

Why is physics so hard to learn?

Many people regard physics as the hardest subject at school, and the reason is well studied. It rarely comes down to a lack of talent, but to how beginners and experts see problems differently. In a classic study, Michelene Chi, Paul Feltovich and Robert Glaser (1981) had physics experts and novices sort problems by similarity. The result: novices grouped them by surface features — "this one has an inclined plane" or "this one has a spring." Experts, by contrast, sorted by the underlying principle — "this is a conservation-of-energy problem" or "here Newton's second law applies." The difference is not calculation speed but how the knowledge is organised: around principles, not around surface appearances.

This is exactly where the second hurdle appears. Every new formula, quantity and unit is another building block your working memory has to hold at once. This cognitive load quickly overwhelms you when you try to juggle formula, method and physical meaning all at the same time. The way out is not to cram faster but to understand the meaning well enough that the formula becomes a logical consequence — then your memory has far fewer separate pieces to carry.

Should I understand physics or memorise formulas?

Understand first — and for a measurable reason. In 1998 Richard Hake analysed data from 62 physics courses with more than 6,500 students, comparing traditional lecturing with interactive teaching in which students had to actively reason through concepts. On a standardised concept test (the Force Concept Inventory), the interactive courses achieved on average about twice the learning gain (0.48 versus 0.23). The second finding is striking: those same students also solved quantitative problems better in the end. So understanding the concept does not just improve your calculations "on the side" — it is the foundation on which reliable calculation is built in the first place.

That does not mean memorising plays no role. A few things have to be solid: core equations, important constants, standard units. But by far the larger part of physics can be derived from a handful of principles. We describe the same shift — away from cramming, toward genuine understanding — for closely related school maths in our piece on understanding maths instead of memorising it; without a solid mathematical toolkit, physics stays hard, because then the foundation is missing in two places at once.

Concepts before formulas: how do you really understand them?

You have understood a concept when you can explain it in your own words without a formula. A proven test for this is the Feynman technique, named after the physicist Richard Feynman: explain a topic simply enough for a child to follow. The moment you stumble or retreat into jargon, you have found the gap where real understanding is still missing.

In practice, "concept before formula" means:

• Ask what every formula means. F = m·a is not "three letters" but "the greater the force, the greater the acceleration — and the heavier the object, the smaller it is."
• Link the formula to a sketch or an everyday situation. A quick drawing with forces, directions and quantities unburdens your memory more than any blunt repetition.
• Derive formulas yourself where you can, instead of just adopting them. Once you understand where an equation comes from, you hardly need to memorise it.

How do you solve physics problems systematically?

You do not learn physics by reading worked solutions but by calculating yourself. That is not an opinion but a robust finding of learning research: Henry Roediger and Jeffrey Karpicke showed in 2006 that active retrieval — solving a problem yourself — improves long-term retention more than re-reading, especially on tests after days or a week. That is exactly the horizon that counts for exams.

A reliable scheme for almost any problem:

1. Sketch and knowns. Draw the situation, note all known quantities with their units, and mark clearly what is being asked.
2. Choose a principle, not a formula. First ask: which physical principle applies here — conservation of energy, force balance, momentum? Only then look for the matching formula. That is how you think like an expert, not like a novice.
3. Solve symbolically, then substitute. Rearrange the equation for the unknown before you plug in numbers. This reduces errors and shows you what the result actually depends on.
4. Check units and order of magnitude — more on that in a moment.

When you get stuck on a problem, the temptation to look up the answer immediately is strong — and that is exactly what weakens the learning effect. It is more helpful to have a counterpart that asks you a pointed question instead of revealing the answer. An AI tutor can take on that role and nudge you onto the solution path with questions, rather than doing the work for you.

Why should you always check the units?

Because units are a free error check that almost everyone skips. Every physical equation must yield the same unit on both sides — this is called dimensional analysis. If you calculate a speed and end up with metres instead of metres per second, you have certainly made a mistake, often a wrongly rearranged symbol.

Two habits save you a lot of marks:

• Carry the units through your calculation. Treat units like factors and cancel them along the way. If the expected unit comes out, the method is very likely correct.
• Estimate the order of magnitude. Before calculating, ask roughly: should the result be 5 or 5,000? A car braking at 300,000 km/h is a calculation error, not a physics miracle.

How do you retain formulas and constants long-term?

For the small, indispensable core of facts — core equations, constants such as gravitational acceleration, standard units — spaced repetition is the most effective method. A large review by Cepeda and colleagues (2006), which evaluated 317 experiments, confirmed that material studied spread out over time is retained far better in the long run than material crammed in a single session. In practice that means: 20 minutes daily beats an all-nighter before the exam.

Flashcards with active recall work well for this core — but be careful: cards must not replace understanding. Useful cards ask about meaning ("what does Newton's second law say physically?") rather than just the bare formula. How closely understanding and targeted fact-learning work together also shows up in the neighbouring subject: our notes on learning chemistry formulas and reactions carry over to physics almost one to one.

What does a good study plan for physics look like?

• Concept first. For every topic, work out the physical meaning before you cram formulas — ideally with a sketch.
• Calculate daily, spaced not stacked. A few problems regularly beat many problems in a single night.
• Mix problem types. Do not do ten of the same kind in a row; mix the topics. That trains the skill of recognising the right principle in the first place.
• Work through your mistakes. Every wrongly solved problem you then understand is worth more than ten correct ones.
• Explain out loud. Explain a solution path to someone with no physics background. If you stumble, you instantly know your gap.

If you want to learn on the go, you can turn your physics notes into a learning podcast, flashcards or a quiz with LearnCastAI — handy for actively recalling concepts you have already understood while on the bus. We collect more subject-specific study strategies in our Subjects & Topics category.

Which mistakes should you avoid?

Three traps cost the most time. First: memorising formulas without knowing their physical meaning — that collapses at every reworded task. Second: only reading worked solutions instead of calculating yourself; that creates the deceptive feeling of competence. Third: not checking the units at the end and giving away avoidable marks. Avoid these three traps and you will learn physics faster and keep it longer.

Conclusion

You do not learn physics through more cramming but through the right order: first understand the concept, then solve problems actively, and check every calculation against its units. Organise your knowledge like an expert — around principles, not individual formulas — and the supposedly hardest subject turns into a logical system where most of it can be derived rather than memorised.