Distance and displacement are two commonly known terms in Physics. Understanding the difference between distance and displacement is difficult for students. Moreover, the examiners also ask questions about distance and displacement in the exams. When we go for a job interview, interviewers can also ask a question about the difference between distance and displacement. If we want to know the difference between these two terms, we will have to thoroughly understand their in-depth concepts. Before understanding the differences between these two terms, we should try to understand some key terms.
Coordinate System
A coordinate system is a system of one or more numbers. These numbers are known as coordinates. We use the coordinate system to uniquely determine the position of the points. It has an origin. We label the origin as zero points. With the help of a coordinate system, we can also label the directions of the positive and negative numbers.
Position
The placement or the location of something is known as its position. We can show it in the form of a number on the axis. In the coordinate system, the location of an object relative to the origin is known as position. Usually, we use the symbol ‘x’ to locate the position of an object.
Reference Frame
It is also known as the frame of reference. For the measurement of the distance or displacement, we use a point of view. This point of view is known as the reference frame. In Physics, the frame of reference consists of the abstract coordinate system and a set of physical reference points. We will have to use these key terms for the description of the distance and displacement. After understanding these key terms, we can easily understand the difference between these two terms.
Difference between Distance and Displacement
The distance and displacement are different from each other based on various variables. We will try to explain all of them one by one.
1. Difference between the Definitions of Distance and Displacement
As distance and displacement are two different terms, therefore, there is also a difference between their definitions. If we move from one point to another point, the complete length of the path between these two points is known as distance. On the other hand, the shortest distance between these two points is known as displacement. In other words, displacement is the direct length between two points. We have to measure this length along the minimum path between these two points.
2. Denotation
To denote a term, we have to use a symbol. For the donation of distance and displacement, we also use two different terms. To denote the distance between two points, we use the symbol ‘d’. On the other hand, if we want to denote the displacement between two points, we will have to use the symbol ‘s’.
3. Distance and Displacement have Different Formulas
We can determine the speed of a body by using distance. We can define speed as the ‘Time rate of change of distance’. By using the formula of speed, we can determine the formula of distance.
Distance = Speed X Time
On the other hand, we can determine the velocity of a body by using displacement. We can define the displacement as ‘Time rate of change of displacement’. We can easily determine the formula of displacement by using the formula of velocity.
Displacement = Velocity X Time
4. Consideration of the direction
If we are going to calculate the distance between two points, we don’t need to consider the direction. On the other hand, if we are going to calculate the displacement between two points, we will have to consider its direction.
5. Quantity
If we don’t require direction for the explanation of a physical quantity, we call it a physical quantity. To describe the distance between two points, we don’t require direction. That’s why it is a scalar quantity. If we require direction for the explanation of a physical quantity, we call it a vector quantity. To describe the displacement, we require direction. That’s why displacement is a vector quantity.
6. Positive or Negative Values
Distance is always positive. Its reason is that it is an absolute value of the displacement. The distance will tell us how far something is from something. It will never tell us the direction. On the other hand, the displacement can be positive or negative. For example, if a body moves from the initial position of 70m and ends at 160m, the difference between their positions will be 160m-70m=90m. This value indicates that displacement is positive. If a body moves from 160m and ends at 70m, the difference between the values will be 70m-160m=-90m. This value indicates that the displacement is negative. The displacement can also be zero. If the initial and ending points of a body are the same, its displacement will be zero.
7. Information about the Route
If you want to move from one point to another points, you require detailed information about the route. You can get detailed information about the route just by measuring the distance between two points. On the other hand, if you want to get an idea about the shortest path between two points, displacement will be helpful to you.
8. Measurement of the path
We can measure the distance and displacement between two points by using non-straight and straight paths. To measure the distance between two points, we will have to use non-straight paths. On the other hand, if we want to measure the displacement between two points, we will have to use straight paths.
9. Difference between Indication of the Distance and Displacement
As we know that to draw the direction of a vector quantity, we use an arrow. The head of the arrow indicates its direction. We know that distance is a scalar quantity. That’s why we can’t indicate it by using the arrow. We can indicate the displacement by using an arrow because it is a vector quantity.
10. Dependence on the Path
If we want to measure the distance between two points, we have to consider its path. It means that we can change the distance between two points just by changing the path. On the other hand, displacement is independent of the path because it depends on the initial and final positions. You may also like to read about the difference between mass and weight.
Common Mistakes and Misconceptions about the Difference between Distance and Displacement
After reading these points, you can easily get an idea of the difference between distance and displacement. Some people have misconceptions about distance and displacement. As a result, they do mistakes while using these two terms. Here, we will discuss common mistakes and misconceptions about distance and displacement.
i. To measure the displacement between two points, we have to use an equation. Some people make a mistake while measuring the displacement. They swap the initial and final positions in the displacement equation. As a result, they get a negative value. They should try to start with the final position. They should also subtract the initial position from the final position.
ii. Some people think that distance and displacement are two names of the same quantity. By reading the above points, they can easily understand these are two different quantities.
iii. Most people are also confused about the selection of the correct coordinate system. They should know that all the coordinate systems are valid. So, they can choose any coordinate system. Anyhow, it will last some effects on the numbers in the calculation. Anyhow, it will not last any effect on the physical meaning of the system.
