Distance

In physics, distance is a distinct quantity from either position or displacement. It is a scalar quantity, describing the length of the path between two points along which the particle has traveled.

It is the shortest distance between initial and final position of the object.

Distance has magnitude only and can be described in terms of a number and unit; for example, 10 metres. Such a quantity defined by a number and a units is called a scalar quantity.

When considering the motion of a particle over time, distance is the length of the particle's path as opposed to displacement which is the change from its initial position to its final position.

For example, a race car traversing a 10 km closed loop from start to finish travels a distance of 10 km; its displacement, however, is zero because it arrives back at its initial position.

EXAMPLE

A person starts walking into a maze, the direction of North. If the starting

point is X, find the distance to point displacement of Y from X.

a) total distance walked = 20 +8+72+75 +20 + 15 + 70 +12 =112m

b) using a scale diagram with 1 cm to represent 10 m

length of XY = 2, 8cm

displacement of Y = 28m

The displacement of Y from X is 28 metres at an angle of 20⁰ South of East