All equation deep-dives
Newton's second law
Forces
AQA 8463
Must recall
ORIGINAL
F = m a
F is the RESULTANT force — add up the forces first, then use F = m a.
Verified against AQA 8463 (2026 spec)
Know the equation
| Symbol | Quantity | Unit |
|---|---|---|
| F | resultant force | N |
| m | mass | kg |
| a | acceleration | m/s2 |
Rearrangements
- a = F / m
- m = F / a
Apply it — mark your own working
Work each one out on paper first, then reveal the mark scheme and tick the marks you actually earned. That is exactly how you should mark past papers.
Q1
2 marks
A resultant force of 30 N acts on a trolley of mass 6.0 kg. Calculate the acceleration of the trolley.
Do the calculation on paper first — then mark it.
Where the marks get lost
- Using one force instead of the RESULTANT force (subtract friction or drag from the driving force first).
- Leaving the answer without the unit m/s2.
- Confusing mass (kg) with weight (N) — F = m a needs mass, not weight.
Exam tip: If the object moves at constant speed, the resultant force is zero, so a = 0. Spotting that saves you a calculation and is a common exam twist.
Still losing marks on the calculations?
I'll go through your working line by line and show you exactly where the marks are — your first lesson is free.