Speed is how fast something moves; acceleration is how quickly its speed changes.
Formulae
Speed $= \dfrac{\text{distance}}{\text{time}}$ · Acceleration $= \dfrac{\text{change in velocity}}{\text{time}}$
Example: a car speeding up from 0 to 20 m/s in 4 s has acceleration $\dfrac{20-0}{4} = 5$ m/s².
Remember
- Speed = distance ÷ time.
- Acceleration = change in velocity ÷ time.