Major Differences Between Distance and Displacement

The words distance and displacement sound similar and seem to have the same meaning; hence, we get confused. But these two terms are significantly different from each other and have different meanings and definitions. The topic difference between distance and displacement is very common in exams too. To understand the distance and displacement differences, we must know the definitions of the terms first. So, let us see what each term means.

Distance: The distance of the object is defined as the total path travelled by the object. It is a scalar quantity, meaning the object’s distance depends only on the magnitude and not on the direction. For example, if a bus travels north for 5 Kms and takes a turn to travel east for another 5 Kms, the complete distance travelled by bus is 10 Kms. Distance is always more than displacement. The value of distance can never be zero or negative. Distance of the object gives complete information of the path travelled by the object. The distance doesn’t need to be a direct path from the source point to the destination point.

Displacement: Displacement of the object is defined as the minimum distance travelled by the object between the starting point of the object and the final point of the object. It is a vector quantity, which means displacement depends on the direction of the object’s motion. For example, if we consider the last example of a bus travelling 5 Kms north and then 5 Kms east, the total displacement will be the length joining the two points.

Let us check our understanding with some simple examples.

Example1: A car moves 4 kms to the east and then turns and moves 2 Kms to the south, then again takes a turn moves 4 Kms to the west and then turns towards the north to move 2 Kms and reaches the point she started. Let us find out what is the distance travelled and the displacement.

The above figure represents the motion of the car. The total distance covered is 4 2 4 2 = 12 Kms. The displacement is 0. Now, the displacement is 0 because the car covered a path of 12 km during the travel, but it was not out of place when the car finished. It is in the same place where it started, so there is no displacement of motion. When we focus our attention on the direction, we notice that the 4 km travelled to the east is cancelled by the 4 Km travelled to the west, and similarly, 2 Km travelled to the south is cancelled by the 2 km travelled the north. So, direction plays an important role in calculating displacement as it is a scalar quantity. Similarly, while calculating distance, the direction of the car can be ignored.

Example 2: A person walks for 100 m in a straight line to participate in a race. He starts from the start point and ends at the finish point. The person walks in a straight line in one direction and finishes the race. In this example, the distance and displacement of the person are equal to 100 m.

Example 3: A bus moves at a speed of 40 km/hr for 3 hours on a straight road. Let us calculate the distance covered and displacement of the bus.

Solution: We know, Distance = Speed x Time

The bus has travelled a distance of 40 km/hr x 3 hrs = 120 km

The bus is travelling in a straight direction, so the displacement is equal to the distance travelled. The displacement of the car is 120 km.

Thus, distance is how much path the object has covered, and displacement is how far the object has moved from its place. The concept of distance and displacement becomes clear if students solve numerical problems by learning the formulas for the calculation.

To understand the concepts better, let us study the distance and displacement differences from the table below. Since we know the meaning of distance and displacement, it is easier to understand the differences.

Differences between distance and displacement

Sl. No	Distance	Displacement
1	Distance is the total path travelled by the object.	Displacement is the shortest distance between the starting point and the final point of the object.
2	The value of the distance is always positive. It can never be negative or zero	The displacement can be negative, zero or positive depending on the factors.
3	Distance is a scalar quantity.	Displacement is a vector quantity.
4	Distance is denoted by the letter ‘d’	Displacement is denoted by the letter ‘s.’
5	The value of the distance is always more than displacement.	Displacement value is always equal to distance value or less than distance value.
6	Distance gives the complete details of the path travelled by the object.	Displacement does not give complete details of the path travelled by the object.
7	When calculating distance, the direction is not considered.	Direction is taken into consideration when calculating displacement.
8	The formula calculates distance Speed x Time	The formula calculates displacement Velocity x Time
9	The distance can be measured on a path, which is not straight.	The displacement can only be measured along a path, which is straight.
10	Distance is not indicated with an arrow.	Displacement is indicated with an arrow.
11	Distance does not decrease with time.	Displacement decreases with time.

The above are the few differences between distance and displacement. Along with the differences, distance and displacement have similarities too. Let us have a look at what those similarities are.

Distance and displacement both require a source point to be measured from.
Distance and displacement have the same units, i.e. meters (m) in S I units.
If the object’s motion is in a straight direction, then both have equal value.
The dimensions are the same for both distance and displacement.

Conclusion

Understanding the concepts is easier and clearer with the above differences in the tabular section and the similarities. Displacement of the object is the minimum distance travelled by the object between the starting point of the object and the final point of the object. Thus, the distance of the object is the total path travelled by the object.