How to Solve Physics Numericals Step by Step (the GRESA Method)

Physics numericals feel hard for a specific reason: the question hands you a story (“a car accelerates from rest…”) and expects you to turn it into an equation. Students who struggle usually don't lack physics — they lack a procedure for the translation. Here is the one that works, known in many classrooms as GRESA: Given, Required, Equation, Solution, Answer.

The method, step by step

1. Given:extract every quantity from the story and write it as a symbol with units. “From rest” means u = 0 m/s. “Uniformly” means constant acceleration. Hidden data lives in the words, not the numbers.
2. Required:write the symbol you're solving for. One line. It stops you answering a question that wasn't asked — a shockingly common way to lose full marks with correct physics.
3. Equation: pick the relation that connects your Given to your Required — and write it in symbols BEFORE any numbers. Method marks attach to this line.
4. Solution: substitute with units attached, and rearrange algebraically before computing where possible.
5. Answer: state it with units and a sanity check — is the size physically reasonable?

A worked example

A car starts from rest and accelerates uniformly at 2 m/s² for 5 seconds. Find the distance covered and its final velocity.

Given: u = 0 m/s, a = 2 m/s², t = 5 s.
Required: s (distance), v (final velocity).
Equations: s = ut + ½at² and v = u + at.
Solution: s = (0)(5) + ½(2)(5)² = 0 + (1)(25) = 25 m. v = 0 + (2)(5) = 10 m/s.
Answer: s = 25 m, v = 10 m/s. Sanity check: average velocity would be (0 + 10)/2 = 5 m/s, and 5 m/s × 5 s = 25 m ✓ — the two answers agree with each other.

That final cross-check is the professional habit: solving the same quantity a second, independent way. When two different routes agree, you can stop doubting.

Where the marks actually die

• Unit mixing. Kilometres in one line, metres in the next. Convert everything to SI units in the Given step, before anything else.
• Numbers before symbols. Substituting immediately makes your working unreadable — to the examiner awarding method marks, and to you when checking.
• Ignoring the words.“From rest”, “comes to a stop”, “at maximum height”, “just leaves the ground” — each is a disguised numerical condition. Train yourself to translate them on sight.
• No sanity check. A car doing 4,000 m/s should embarrass you into finding the slipped decimal. An answer without a plausibility glance is a coin flip.

How to practise numericals (not just read them)

Reading worked solutions feels like studying and mostly isn't. The loop that works: study one worked numerical until every line makes sense, close it, and re-solve from a blank page with the full GRESA structure. Then do unseen problems of the same type under time. If you get stuck mid-problem, get the specific step explained — not the whole solution handed over. That's the exact use case BrainDrill's tutor was built for: photograph the numerical, see it worked step by step with each step named, ask “why that equation?” until it clicks — and it verifies its result before showing you, because a confidently wrong solver is worse than none. Then close the app and blank-page it. The tool teaches; the blank page is where you learn.