Through thorns to physics: why it seems difficult and what helps

Physics is a subject that either makes you fall in love with it from the first lesson or becomes the most incomprehensible one on the timetable. This is a pity, because its aim is simple: to explain the laws of the world to which we are subject every day and sometimes every second.

The teacher is often blamed — and sometimes with justice: it really is hard to tell about modern science in such a way that it stays alive. But more often the cause lies elsewhere.

Physics is begun with a formula and not with a phenomenon. A pupil is given s = vt before he has had time to notice that a body that moves for twice as long covers twice the distance. The formula at that moment is not the result of an observation but a set of letters that have to be memorised. They can be memorised; they cannot be applied.

The second cause is more honest: physics rests on mathematics. If fractions, powers and proportions have not yet become familiar, then in a physics problem there will be no strength left for the physics itself — it will all go on arithmetic.

A few methods that work regardless of who teaches and how.

• Start with the phenomenon. Before taking a formula, describe in words what is happening: what is moving, what acts on what, what is changing. The formula should be the last step, not the first.
• Check the dimensions. If the answer comes out in metres where seconds were expected, the mistake has already happened, and it has to be looked for in the derivation, not in the arithmetic. This is the cheapest check there is.
• Estimate the order of magnitude before calculating. The speed of a pedestrian is about a metre per second, the density of water is a thousand kilograms per cubic metre. If a calculation gives a speed of a kilometre per second, the answer need not be worked out to the end.
• Work through solved problems in reverse. Take a ready solution and at each step ask: why exactly this formula, which condition of the problem permitted it. Retelling someone else's solution teaches nothing; analysing it does.
• Draw. A diagram with the forces, vectors and axes marked solves half of the problems in mechanics before the first line is written.

Reference materials will also be useful: the reference of quantities, formulas by section and problems with worked solutions.

Practice shows a simple thing: persistence is the main factor of success in physics. Even topics with multi-stage mathematical derivations yield to the person who returns to them a second and a third time. “Not gifted” almost always means “not enough approaches”, not a lack of ability.