Equations of motion

Need to know

What you need to know

• **Speed** is the total distance travelled per unit time (a scalar quantity).
• **Velocity** is the rate of change of displacement (a vector quantity). The sign (+ or -) indicates direction.
• **Acceleration** is the rate of change of velocity (a vector quantity).
• Example: If 'up' is the positive direction, an object moving upwards at 5 m/s has a velocity of +5 m/s. An object moving downwards at 5 m/s has a velocity of -5 m/s. Both have a speed of 5 m/s.

Explanation

Equations of motion

1. **Speed** is the total distance travelled per unit time (a scalar quantity).
2. **Velocity** is the rate of change of displacement (a vector quantity). The sign (+ or -) indicates direction.
3. **Acceleration** is the rate of change of velocity (a vector quantity).
4. Example: If 'up' is the positive direction, an object moving upwards at 5 m/s has a velocity of +5 m/s. An object moving downwards at 5 m/s has a velocity of -5 m/s. Both have a speed of 5 m/s.