Students who struggle with mechanics usually don't struggle with the algebra. They struggle because they drew four forces when there were three.
Draw the body alone
Isolate one object. Every force must come from something touching it, or be gravity. Ask the tutor to name the source of each arrow. If it can't, the arrow shouldn't be there.
Then choose axes deliberately
On an incline, tilt the axes. Ask for the board to redraw with rotated axes side by side with the standard version. The number of terms you have to resolve visibly drops.
Practise on the awkward cases
- Two blocks connected over a pulley
- A body in a lift, accelerating up and down
- Circular motion at the top and bottom of a loop
Guides are written by the Santi learning team and updated each term as exam boards change. Spotted something out of date? Tell us.