Difference Between Distance and Displacement with Examples
Distance and displacement are two central concepts in the study of motion in Physics. While they often sound similar, their definitions and usage are quite distinct. Understanding these differences is important for building a strong foundation in mechanics and solving real-world motion problems with accuracy.
Distance represents the total length of the path traveled by an object, regardless of the direction taken. It quantifies “how much ground” has been covered during motion. Conversely, displacement is defined as the shortest straight-line distance from the initial position to the final position of the object, and it considers the direction of that movement.
To make the difference clearer, let’s consider a common Physics example: Imagine a person walks 4 meters east, 2 meters south, 4 meters west, and finally 2 meters north. The total distance is the sum of all these movements, but the displacement is based on the net change from the start to end point.
| Concept | Distance | Displacement |
|---|---|---|
| Definition | Total length of path traveled, irrespective of direction | Shortest straight-line distance from start to end with direction |
| Quantity Type | Scalar (no direction) | Vector (has direction) |
| Can be negative? | No | Yes |
| Can it be zero? | Only if no movement | Yes, if start and end points are the same |
| Example | Walking 10 meters in a circle | Start and finish at the same spot, displacement is zero |
Let’s analyze the earlier example step by step:
- Walk 4 m east
- Walk 2 m south
- Walk 4 m west
- Walk 2 m north
Total Distance: Add all path segments: 4 m + 2 m + 4 m + 2 m = 12 m.
Total Displacement: Net east movement: 4 m east - 4 m west = 0 m.
Net north movement: 2 m south - 2 m north = 0 m.
So, the final position is exactly at the starting point—displacement is 0 m.
Distance always shows the amount of travel, while displacement shows the overall change in position along a straight line with direction considered. This distinction is vital when calculating and interpreting motion.
| Quantity | Symbol | SI Unit | Formula |
|---|---|---|---|
| Distance | d | meter (m) | Sum of all path segments (e.g., d = d1 + d2 + …) |
| Displacement | Δx | meter (m) | Δx = xfinal - xinitial |
Let’s solve another example. A cross-country team starts at their school, runs 10 miles, and finishes back at the school.
- Distance: 10 miles (path covered)
- Displacement: 0 miles (starts and ends at same point)
Now consider this scenario: A coach walks 55 yards left from a starting point and stops. In this case, both distance and displacement are 55 yards left, since movement happens in one straight direction.
In summary, distance accumulates regardless of changes in direction, while displacement can increase, decrease, reach zero, or become negative whenever direction changes. For paths that return to the starting point, displacement is always zero, but distance equals the full journey.
| Step | Action |
|---|---|
| 1 | Identify total path covered for distance. Add each segment regardless of direction. |
| 2 | For displacement, check start and end points. Draw a straight line (with direction) between them and calculate the net change. |
| 3 | If motion returns to start, displacement is zero. Otherwise, use subtraction: final position minus the initial. |
For more detailed discussions and comparison tables, students can read Difference Between Distance and Displacement or explore vectors in detail at Displacement and Distance Vectors. For step-by-step graph analysis, refer to Distance Time Graphs.
Practice more using Distance and Displacement Practice Questions and strengthen your understanding with Path Length, Position and Displacement Concepts.
Mastering these concepts is essential for solving mechanics problems involving motion. Always identify what is being asked—distance or displacement—and apply the appropriate logic. Use tables and simple breakup of motion to clarify answers.
FAQs on Distance and Displacement Explained for Physics Students
1. What is distance in physics?
Distance in physics refers to the total length of the path traveled by an object from start to finish, regardless of the direction taken. It is a scalar quantity, always positive or zero, and is measured in metres (m).
2. What is displacement?
Displacement is the shortest straight-line distance from the initial position to the final position of an object, including the direction. It is a vector quantity, can be positive, negative, or zero, and is measured in metres (m).
3. What is the difference between distance and displacement?
Distance is the total path length traveled without considering direction (scalar), while displacement is the straight-line distance between the start and end points, taking direction into account (vector).
Key differences:
- Distance is always positive; displacement can be zero or negative.
- Distance does not consider direction; displacement does.
- Distance is usually more than or equal to displacement.
4. Is distance always greater than or equal to displacement?
Yes, the distance covered is always greater than or equal to the displacement. Distance equals displacement only in straight-line motion without changing direction.
5. Can the displacement of an object be zero even if it has travelled a distance?
Yes, displacement can be zero if the object returns to its starting point, even though it has covered a certain distance. For example, running a full lap around a circular track brings the displacement to zero, even though the distance equals the total circuit length.
7. How do you represent distance and displacement graphically?
Distance is shown as the total length of the path on a motion diagram, while displacement is shown as a straight arrow (vector) from the initial point to the final point. On a graph, distance-time graphs always rise or stay flat, but displacement-time graphs can rise, fall, or remain flat based on direction changes.
8. Can displacement be negative? If yes, when?
Yes, displacement can be negative if the final position of an object is on the negative side of the reference point or in the opposite direction from where it started. Sign always indicates direction.
9. What are some real-life examples of distance and displacement?
Example 1: Walking 4 m east and then 3 m west – total distance is 4 + 3 = 7 m; displacement is 4 – 3 = 1 m east.
Example 2: Completing a full circle (e.g., 400 m) and stopping at the starting point – distance is 400 m, but displacement is 0.
10. Why is distance called a scalar quantity and displacement a vector quantity?
Distance is a scalar because it only has magnitude and no direction. Displacement is a vector because it has both magnitude and direction, describing not just how much but also in which way an object has moved.
11. How to solve distance and displacement numericals step by step?
Steps to solve:
- Draw the motion path diagram.
- Mark and label initial and final positions.
- Add each segment for total distance.
- Use the shortest straight line for displacement.
- Express answers with correct SI units and direction for displacement.
12. Where can I practice more questions on distance and displacement?
You can practice more questions and worksheets using Vedantu’s Physics resources for distance and displacement concepts, including solved examples and MCQ practice aligned to the latest syllabus.
