Momentum
Start here
Lesson overview
Computing momentum from mass and velocity.
Go to lesson quiz →Exam guidance · WAEC WASSCE Paper 1 + Paper 2 Lens
Core idea (Kinematics,SUVAT & Newton's Laws of Motion): Pick a positive direction first, list knowns/unknowns (u, v, a, s, t), draw the free-body diagram before writing ΣF = ma, and check vector signs.
Pacing
Objective speed on Paper 1 + structured step-by-step method marks on Paper 2 Theory/Practical.
How WAEC marks this
Examiners award method marks (M1) for stating the formula/definition and accuracy marks (A1) ONLY when SI units are written.
Watch out for
Writing bare numbers without working or omitting SI units loses up to 50% of Paper 2 marks even when the final value is right.
Lesson content
Overview — Momentum
Computing momentum from mass and velocity. This lesson is at the beginner level — by the end, you'll be able to recognise this question type, apply a reliable method, and avoid the traps that cost marks.
Key Concept
Momentum is a measure of how hard it is to stop a moving object. It is calculated as p = mv, where m is mass in kg and v is velocity in m/s. Momentum is measured in kg·m/s.
Why It's Tested This Way
Momentum questions build directly into collision and conservation-of-momentum problems at a higher level, so examiners test the basic formula first to confirm you can apply p = mv confidently before layering on complexity.
Method
To find momentum, simply multiply mass by velocity — there's no need to rearrange anything unless the question asks for mass or velocity instead.
Worked Example
Worked example: A 1,200 kg car moving at 15 m/s has momentum = 1,200 × 15 = 18,000 kg·m/s.
Second Worked Example
Second worked example: A 5 kg object moving at 4 m/s has momentum = 5 × 4 = 20 kg·m/s.
Common Traps
Common trap: momentum has both a magnitude and a direction (it's a vector) — in collision questions, momentum lost by one object equals momentum gained by another, but direction (positive/negative) must be tracked carefully.
Lesson Summary
Remember: (1) identify what is being asked, (2) apply the WAEC strategy, (3) check against the traps. Complete the 10-question quiz below to unlock the next lesson — you need at least 60% to pass.
Mastery Check · Lesson Quiz · pass 60%
Sign in to take the quiz and track your progress.
Create a free account to take quizzes, earn checkpoints and track your scores — no card needed.
Create your free account