Acceleration

Acceleration definition

Rate of change of velocity

Vector quantity

Has magnitude and direction

Formula

Acceleration = change in velocity ÷ time

Symbol

a

SI unit

m/s²

Change in velocity

Final velocity − initial velocity

Positive acceleration

Speeding up

Negative acceleration

Slowing down (deceleration)

Zero acceleration

Constant velocity

Acceleration when turning

Direction changes → still accelerating

Average acceleration

Δv ÷ Δt

Instantaneous acceleration

Acceleration at a specific moment

High speed ≠ high acceleration

Acceleration depends on change in velocity, not velocity itself

Example

Velocity increases from 0 to 5 m/s in 10 s → acceleration = 0.5 m/s²

Graph meaning

Slope of velocity–time graph gives acceleration

Uniform acceleration

Velocity changes by equal amounts in equal times

Deceleration meaning

Acceleration in opposite direction to motion

Key idea

Acceleration occurs whenever speed or direction changes