Equation-hunting is a trap that works just often enough
It gets you through easy problems, which is why it survives. It fails completely on any problem that requires you to notice which physics applies — and those are the ones that carry the marks, because they are the ones that distinguish candidates.
The habit worth building
- Draw the situation. Always. A free-body diagram, a circuit, a before-and-after sketch. The diagram is where the physics gets decided.
- Say what's conserved, in words. Energy? Momentum? Charge? This one sentence solves a surprising fraction of problems before any algebra.
- Predict the answer's shape before computing it. Should it grow or shrink with mass? What happens as the angle goes to zero? You now have a check on your algebra that costs ten seconds.
- Only now, the equations. And they should feel like a consequence of the picture, not a substitute for it.
Units and limits will catch most of your errors
Dimensional analysis is nearly free and finds a large fraction of algebra mistakes. So does taking a limit: set a variable to zero or infinity and see whether the answer does something sensible. Students who do this routinely make far fewer of the careless slips that cost them marks they'd already earned.