Trolley A of mass 2.0 kg moves at 3.0 m/s and collides with a stationary trolley B of mass 4.0 kg. The trolleys stick together after the collision. Calculate their common velocity after the collision.
[4 marks]
Total for this question: 4
All equation deep-dives
Momentum
Forces
AQA 8463
On the equation sheet
ORIGINAL
Higher tier
p = m v
Higher tier: in a collision, total momentum before = total momentum after. Track the whole system.
Current GCSE 8463 policy: The full AQA GCSE Physics 8463 equation sheet is provided with both papers in 2026; use fluency practice to learn selection and rearrangement, not to memorise the list.
Board and spec code confirmed against AQA 8463 · registry checked 2026-07-17How this checking works
Know the equation
| Symbol | Quantity | Unit |
|---|---|---|
| p | momentum | kg m/s |
| m | mass | kg |
| v | velocity | m/s |
Rearrangements
- m = p / v
- v = p / m
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
Do the calculation on paper first — then mark it.
Where the marks get lost
- Forgetting the stationary object still counts (its momentum before is 0, but its mass joins the total after they stick).
- Using only one trolley's mass for the combined object after they stick together.
- Dropping the direction: momentum is a vector, so opposite directions need opposite signs.
Exam tip: Write 'total before = total after' as your first line every time. In a stick-together collision the masses add, so the moving object slows down — sanity-check that your answer is smaller than the starting speed.
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