Is physics hard? How hard high school physics, AP Physics and college physics really are, what makes it hard, how it compares with chemistry, biology and math, a ten-question readiness check, and the four things that decide it for you

"Is physics hard" is searched by students choosing next year's courses, by parents watching a child who has always been fine in science suddenly struggle, and by college students facing a required physics sequence. The honest answer is yes, for most people, and for a reason that is useful to know: physics is hard in a different way from every other school subject, and once you know the way, you can prepare for it.

The honest answer

Physics is the subject with the fewest facts and the most thinking. A whole semester of mechanics rests on a handful of principles: Newton's three laws, the conservation of energy and of momentum, and a few definitions. There is almost nothing to memorise. What there is instead is a test, every single time, of whether you can take a situation you have never seen, work out which of those few principles applies, draw it, and turn it into math.

That is why physics feels hard to students who have been successful by working hard. Working hard at memorising does nothing in physics. The students who find physics easy are rarely the ones with the best memories; they are the ones with the most fluent algebra and the habit of drawing before they calculate.

So the useful answer to "is physics hard" is: it depends on four things, and talent is not one of the big ones. They are listed below, after the courses.

Course by course

Why the first course matters most. Every course in the table starts with mechanics: motion, forces, energy, momentum. Everything after is built on it. A student who gets through mechanics with the principles understood finds electricity, waves and the rest harder in content but easier in method, because the method is the same. A student who survived mechanics by matching problems to examples hits a wall in the second unit that uses a new example set.

What makes physics hard

1. There is nothing to memorise, so memorising fails. Students arriving from biology and chemistry bring a method that worked: learn it, recall it. Physics gives them five principles and a hundred different situations, and the method stops working in the first month.

2. Every problem is a reading problem first. Before any math, you must turn a paragraph about a block on a ramp into a picture with forces drawn on it. Students skip this step because it looks like it is not the real work. It is the real work.

3. The math is inside every topic. In chemistry the calculations arrive in certain chapters. In physics every chapter is math: rearranging formulas, solving two equations at once, trigonometry for every force at an angle, graphs read for slope and area. The math is a level below the student's math class, but it has to be automatic, because the attention is needed for the physics.

4. Units, signs and diagrams carry marks. A right method with the wrong sign for a direction, or a velocity in kilometres an hour where metres per second were needed, gives a wrong answer that looks right. Physics punishes carelessness more than any other science.

5. Intuition is often wrong. Heavy things do not fall faster. A ball thrown upward has the same acceleration at the top as on the way down. The hardest part of mechanics for many students is not learning the right ideas but unlearning the ones they arrived with.

Physics against other subjects

A readiness check

Ten minutes, no calculator. This checks the math and habits physics assumes, not physics itself.

1. Rearrange v = u + at to make t the subject
2. Rearrange s = ½at² to make a the subject
3. Solve the pair: x + y = 10 and x − y = 4
4. A 5 m ladder leans against a wall at 60° to the ground. How high up the wall does it reach? (sin 60° is about 0.87)
5. Convert 72 km/h to m/s
6. On a distance-time graph, what does the slope mean? On a velocity-time graph, what does the area under the line mean?
7. What is 3 × 10⁴ multiplied by 2 × 10⁻²?
8. If y is proportional to x², what happens to y when x doubles?
9. A car speeds up from rest to 20 m/s in 4 s. What is its acceleration?
10. Draw a box on a table. Draw and label every force acting on the box.

Answers: 1) t = (v − u) / a 2) a = 2s / t² 3) x = 7, y = 3 4) about 4.3 m 5) 20 m/s 6) speed; distance travelled 7) 6 × 10² or 600 8) it becomes four times larger 9) 5 m/s² 10) two forces: the weight of the box downward and the normal force from the table upward, equal in size; nothing else unless the box is pushed.

Nine or ten: physics will be work, not a wall. Six to eight: a month on the ones you missed, before the course starts, will change your year. Five or fewer: the math needs fixing first, and most of the struggle you would have in physics would really be an algebra struggle.

Four things that decide how hard it is for you

1. How automatic your algebra is. Rearranging a formula with three symbols in it, solving two equations at once, working with powers of ten. If these take thought, there is no attention left for the physics. This is by far the largest factor.
2. Whether you draw. Students who draw every problem before writing an equation score higher at every level, and the difference is large. Drawing is not a preliminary; it is where the physics happens.
3. How you practise. Reading worked solutions feels like learning and is not. Physics is learned by attempting problems, getting them wrong, and finding out why. Twenty minutes a day beats a long session once a week. The method is set out in how to study physics.
4. Which course and what pace. A regular high school course over a year is a different experience from the same content in a college semester, or from AP Physics C taken alongside calculus. Choose the course that matches your math, not your ambition.

Talent is on the list somewhere, but a long way below these four.

The month before you start

• Week 1: rearranging formulas, twenty a day, until it is automatic.
• Week 2: simultaneous equations and powers of ten; converting units.
• Week 3: the sine, cosine and tangent of the common angles, and splitting a line at an angle into horizontal and vertical parts.
• Week 4: graphs: slope and area, read from a line, with units.

Then, from the first week of the course: draw every problem, write every step with its unit, and attempt the homework before looking at any example.

If you are already in it and struggling

Do not reread the chapter. Take one marked test and sort every lost mark into four piles: did not know which principle to use; drew nothing or drew it wrong; math error; units or sign. For most students the first two piles are the biggest, and they are fixed by practising the start of problems, not the end. The four reasons students fall, in the order they happen, are in why is physics so hard.

Where to get help

A 1-on-1 online physics class with a tutor who holds a master's in physics: the readiness check in the first class, the algebra fixed alongside the course rather than instead of it, and every diagram and every line of working read before the next class. For regular and honors physics, AP Physics 1, 2 and C, IGCSE, A-level, IB and CBSE Class 11 and 12. The free 30-minute first class is a real lesson on the problem you bring.

Questions parents ask

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