**Distance** travelled by an object is the length of path taken.

- SI unit is metre (m)
- Scalar quantity
- Can never be negative and distance travelled will never decrease

**Displacement** is the shortest distance from the initial to the final position of an object.

- SI unit is metre (m)
- Vector quantity
- Can be negative

## Distinguishing Between Distance and Displacement

If you have problems grasping the difference in concept of displacement and distance travelled, please study the example below.

### Consider the diagram above:

**Difference between distance and displacement:** If an object started travelling from B to C and **ends** at D, distance travelled is BC + CD. Displacement is BD.

**Displacement can be ZERO:** If the object started travelling from B to C to D and **ends** at B, distance travelled is BC + CD + DB. Displacement is ZERO. (The object ends at the same place it started)

**Displacement can be NEGATIVE:** If the object travels from B to A, the displacement is negative. By CONVENTION, the direction towards the right and top are positive. A way to remember: Go right = positive, go left = negative.

## Examples

### Ali walked 1 km to the North, then 1 km to the East and followed by 1 km to the South. What is the distance covered by Ali? What is his final displacement?

**Show/Hide Answer**

Distance: $1 + 1 + 1 = 3 \, \text{km}$

Displacement: 1 km east of starting point.

### A car travelled from point O to D along the curved path OABCD. What is (a) the distance travelled by the car, and (b) the displacement of the car?

**Show/Hide Answer**

The distance travelled by the car is OABCD.

The displacement of the car from point O is OD (to the right of O).

In VELOCITY how equation V=S/T consist of S=DISPLACEMENT???

I don’t get how displacement can be negative…Can u please explain soon?

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We usually take displacement to the right as positive.

Hence, if displacement is negative, we will interpret it as the object is currently at the left-side of the initial point.

Thanku