Distance and displacement are two commonly known terms in Physics. To understand the difference between distance and displacement is difficult for the 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 the 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 other points, 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 ‘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
other 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:
Difference between scalar and vector quantities
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 the distance and displacement.
·
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.
·
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.
·
Most of the
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.
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