Definition
Distance is the total length of the path travelled by an object during its motion.
It describes the total path length covered by the object, regardless of where the motion starts or ends.
Distance depends only on the actual path taken. Every part of the path contributes to the total distance.
Distance is a scalar quantity, so it has magnitude only and no direction.
SI Unit
The SI unit of distance is the meter (m). Other units, such as kilometers (km), centimeters (cm), and millimeters (mm), are also commonly used depending on the scale of the motion.
Calculating Distance
If an object moves along several sections of a path, the total distance is the sum of the lengths of all sections.
Distance = Length of Path 1 + Length of Path 2 + Length of Path 3 + …
Example 1
A student walks:
- 6 m east,
- then 4 m north.
The total distance travelled is
Distance = 6 m + 4 m = 10 m
Example 2
A runner completes one full lap around a circular track. The circumference of the track is 400 m.
Distance = 400 m
Key Points
- Distance is the total length of the path travelled.
- Distance is a scalar quantity.
- Distance has magnitude only.
- Distance can never be negative.
- The SI unit of distance is the meter (m).