Equations of Motion
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Lesson overview
Computing final velocity from initial velocity, acceleration and time (v = u + at).
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 — Equations of Motion
Computing final velocity from initial velocity, acceleration and time (v = u + at). This lesson is at the advanced 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
The equation v = u + at links final velocity (v), initial velocity (u), acceleration (a), and time (t) for an object moving with constant acceleration.
Why It's Tested This Way
This is the simplest of the 'equations of motion' and is tested as a foundation for harder motion problems (like those combining distance and acceleration) at Advanced level.
Method
To find the final velocity, multiply acceleration by time, then add the initial velocity.
Worked Example
Worked example: A car starting at 5 m/s accelerates at 2 m/s² for 4 seconds. Final velocity = 5 + (2 × 4) = 5 + 8 = 13 m/s.
Second Worked Example
Second worked example: An object starting at 8 m/s decelerates at 1 m/s² for 3 seconds: final velocity = 8 + (−1 × 3) = 5 m/s — a negative acceleration (deceleration) reduces the final velocity.
Common Traps
Common trap: forgetting to multiply acceleration by time before adding the initial velocity — always multiply first, then add.
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.
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