Acceleration is the rate of change of velocity,

a = (v − u)/t.

Use metres per second squared; a negative value relative to the chosen positive direction is not automatically motion backwards.

For uniform acceleration, use v² − u² = 2as when distance is given; this equation is available on both tiers.

Example: A vehicle starts at 4 m/s and accelerates uniformly at 2 m/s² over 12 m.

Find final speed. v² = u² + 2as = 4² + 2 × 2 × 12 = 64; v = √64 = 8 m/s. Use clear labels. Avoid unjustified claims.