Mechanics rewards depth more than breadth, because so much of it is the same few principles wearing different clothes. Recognising which principle a question is really about is most of the work.
The principles that keep reappearing
- Conservation of energy — turns a two-stage problem into a one-line comparison of start and end.
- Conservation of momentum — every collision, and most problems involving two bodies interacting.
- Newton's second law with a free-body diagram — unglamorous, and the reason most force questions become tractable.
- Rotational analogues — torque, moment of inertia, angular momentum. Once you see that they mirror the linear equations, half the work is already done.
Draw the free-body diagram, always
Not sometimes. Not when it looks hard. Every force question, every time.
The diagram is where a missed normal force or a wrong friction direction becomes visible, and those are the errors that produce an answer matching one of the wrong options — which is far worse than producing nonsense, because nonsense you notice.
Energy before kinematics
When a question gives you positions and speeds but not time, it is usually an energy question wearing kinematic clothes. Reaching for the equations of motion turns a one-step problem into three.
The tell: if time is neither given nor asked for, try energy first.
Where the time goes badly
Candidates routinely over-invest in elaborate pulley systems and under-invest in circular motion and rotational dynamics, which appear more often and are more predictable.
Check your own distribution against past papers rather than against how interesting you find each topic.
The habit that saves the most marks
Before computing anything, ask what the answer should look like. Faster or slower than the input? Larger or smaller than the obvious estimate? An answer that contradicts that expectation is usually an algebra error, and you have caught it in five seconds.