Motion is the change in position of an object with respect to time.

The quantities of motion are:

1. DISTANCE

• Distance is the length between two points.
• The standard symbol for distance is (s) and SI unit is metre (m).
• For example a boy runs a distance of 100m.
• Distance is a scalar i.e. it has magnitude (or size) only.

2. DISPLACEMENT

• Displacement is the distance travelled in a stated or particular direction.
• The standard symbol for displacement is (s) and SI unit is metre (m).
• For example a boy runs a distance of 100m in the south east direction.
• Displacement is a vector i.e. it has magnitude (or size) and direction.

3. SPEED

• Speed is the distance travelled per unit time.
• The standard symbol for speed is (v) and SI unit is metre per second (m/s).
• For example a boy is running at 5m/s.     

VELOCITY                             

• Velocity: is the distance travelled per unit time in a stated particular direction.
• The standard symbol for speed is (v) and SI unit is metre per second (m/s).
• For example a boy is running at 5m/s in the south east direction.

5. ACCELERATION

• Acceleration is the rate of change of velocity (speed). 

• The standard symbol for acceleration is (a) and SI unit is metre per second squared (m/s²).

• Acceleration is a vector i.e. it has magnitude (or size) and direction.

• Acceleration can either be positive or negative.

• Negative acceleration is also known as deceleration or retardation.

• Acceleration is calculated as:

$$ \text{a} = \frac{\text{v} – \text{u}}{\text{t}} $$