Reference Frames

The motion of an object is always considered with the reference to a time and position frame called as reference frame. The object takes a uniform or non uniform velocity with a particularly visible frame of reference. The frame of reference is considered to be the surface of the earth for all practical purposes. 

For instance, in consideration of the movement of the objects, the surface of the earth is assumed to be the frame of reference and all the motion is considered with reference to the static point taken on the earth’s surface. The objects may be either in the same or opposite direction. Relative motion can be considered either along a straight line or in a plane, in multiple dimensions. 

Relative Motion

Relative Motion is defined as the motion of an object when observed with respect to another object which may be either at rest or in motion. The concept of motion is relative in nature rather than absolute. As per the definition of motion, a body is said to be in motion or at rest if it changes its position with respect to the observer or a stationary object. This can be understood from the following example

Example of Relative Motion: Suppose you and your friend are traveling on a train sitting together and a boy standing alongside the track is observing you. Both of you don’t change your position with respect to each other hence both of you are at rest with respect to each other but with respect to the boy who was standing outside you and your friend are in motion because your position is changing with time.

Table of Content

  • Relative Motion Definition
  • Relative Velocity
  • Reference Frames
  • Motion in One Dimension
  • Relative Motion in One Dimension
  • Motion in Two Dimensions
  • Relative Motion in Two Dimensions
  • Relative Motion Problems

Hence we observe that the state of motion is different for different observers making motion a relative concept rather. The difference in the observation of the boy standing outside and you sitting inside is because of the different Frames of Reference.

Similar Reads

Relative Motion Definition

When the motion of an object is observed with respect to some other object either at rest or in motion, i.e., either a moving or stationary object, then the motion of the first object is called relative motion with respect to the second object....

Relative Velocity

The relative velocity of the body comes into consideration when the other object moves either in the same or opposite direction. The speeds of the involved objects may be increasing, decreasing, or constant with reference to each other....

Reference Frames

The motion of an object is always considered with the reference to a time and position frame called as reference frame. The object takes a uniform or non uniform velocity with a particularly visible frame of reference. The frame of reference is considered to be the surface of the earth for all practical purposes....

Motion in One Dimension

Motion in one dimension or straight line refers to the displacement of an object with respect to time while the object moves along a straight path. This type of motion is also called linear motion. It is a uni-dimensional motion and can be well expressed using the X-axis coordinate or Y-axis system alone I.e. position is a function of either the x-coordinate or y-coordinate. For instance, The car moving along the same path as shown below:...

Relative Motion in One Dimension

In the case of relative motion in one dimension, the two objects must be in motion along the same axis but the motion and the velocity of the two objects can be either in the same or opposite direction. Hence, the following two cases arise:...

Motion in Two Dimensions

It is defined as the motion in which the position of an object is given by a pair of coordinates i.e. x and y. When a body will move in the plane the coordinates of the position will change. For example, if a body is moving in an X-Y plane then the position of the body is given as \vec{r} = x\hat{i}+y\hat{j}...

Relative Motion in Two Dimensions

Consider two objects P and Q moving in a plane with positions XP(x1,y1) and XQ(x2,y2). The velocities of these two objects can be determined by differentiating the position vector with respect to time ‘t’....

Relative Motion Problems

Problem 1: Athletes are participating in a relay race on the track, running with respective velocities of [Tex]\vec v_c           [/Tex] and [Tex]\vec v_{rel}           [/Tex]. Compute the relative velocity....

Relative Motion – FAQs

What is Relative Motion?...