Calculating Uniform Acceleration — Movement & Position | IGCSE Physics

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 12% of your exam marks.

stable

High

Stable12%

Distance-time graphs, speed calculations and velocity appear in nearly every series.

Uniform acceleration means the acceleration is constant throughout the motion
When you know any three of (initial speed, final speed, acceleration, distance) but not the time, the following equation links them in one line:

v² = u² + 2as

where:
- u = initial speed (m/s)
- v = final speed (m/s)
- a = acceleration (m/s²)
- s = distance moved (m)
All four quantities must be in SI units before substituting

Formula triangles only work for simple multiply/divide equations; v² = u² + 2as contains a square and a sum, so triangles are no help
Use ordinary algebra: subtract u² from both sides, divide both sides by 2a, or take a square root, depending on which letter is the subject. Whatever you do to one side, do to the other

Worked example

Using v² = u² + 2as to find braking distance

A vehicle travelling at 20 m/s brakes to rest with a deceleration of 5 m/s². Find the braking distance.

Solution: