What is position in physics?
In this tutorial, we will learn about the position in physics and how to find position of a particle or object in physics. The concept of position in science or physics is a starting point in the study of physics and is introduced while studying kinematics.
If we want to describe the motion of an object, we measure the position, distance, velocity and other such parameters of the object.
The position of a particle in physics is the place where it is being placed. Generally, this place can be located on a number line when motion we are studying is in one dimension.
The position of an object is measured from some fixed point known as reference point.
For example, if a person says the bus is moving, it means that the bus is changing its position with respect to that person in a given time interval. In this case, the person is the reference point.
A reference point or origin is defined as a fixed point or fixed object with respect to which the given body changes its position.
Finding Position in number line
To describe the position of the particle at a given time we have to specify
Its distance from the origin and whether it is in positive direction or negative direction as seen from the origin.
Let us now consider an example where a man starts walking towards the right of the tree. At (t = 5) minutes he covered a distance of 10 meters and then start moving towards the left.
Now at time( t = 8) minutes, he is at a distance of 5 m from the origin.
We will now mark positions of the man at two given instants of time.
Here in the above figure O is the origin. This position is the starting position of man. Values to the right of the origin are positive and to the left of origin are negative.
Now at t equals to 5 minutes the man is at 10 m from the origin. So, point A in this figure gives the position of the man at this time.
Now he starts moving towards left and at t equal to 8 minutes he is 5 m from the tree or origin. This position is represented by point B.
The position of man can be negative in the sense that if he keeps moving towards left crossed the tree and is at 4m towards the left of the tree. At this time (t = 15) minutes his position is represented by point C on the line which is negative.
Hence if the position of the man is at 2 m from the tree or origin in a negative direction or towards left then his position is at (x = -2) meters. If he is at two meters from the origin towards the right or in a positive direction then his position is at (x = 2) meters. Here quantity x is called the position of the body.
For more information watch this video on position, distance and displacement.