RELATIVE MOTION
[THEORY]
Relative Motion of Objects:
Same direction
When two objects are moving in the same direction, the relative speed is the difference between their
speeds.
Example:
If a train A is moving at 80 km/h and another train B is moving at 60 km/h in the same direction, the
relative speed of train B with respect to train A is 20 km/h.
Opposite Direction
When two objects are moving in opposite directions, the relative speed is the sum of their speeds.
Example:
If a train A is moving at 80 km/h and another train B is moving at 60 km/h in the opposite direction, the
relative speed of train B with respect to train A is 140 km/h.
Equations of Relative Motion: Position, Velocity, Acceleration Fixed vs. Moving Reference Frames
A reference frame is a set of coordinates and an origin from which we measure the position of objects.
A fixed reference frame is one that is not accelerating, such as the ground or the stars.
A moving reference frame is one that is accelerating, such as a car or a plane.
• Relative Motion Between Two Particles
Relative motion is the difference in motion between two objects.
To find the relative position of one object with respect to another, subtract the position of the second
object from the position of the first object. Similarly, to find the relative velocity of one object with
respect to another, subtract the velocity of the second object from the velocity of the first object.
The relative acceleration of one object with respect to another is found in the same way as relative
velocity.
It is important to note that the equations of relative motion depend on the choice of reference frame.
[THEORY]
Relative Motion of Objects:
Same direction
When two objects are moving in the same direction, the relative speed is the difference between their
speeds.
Example:
If a train A is moving at 80 km/h and another train B is moving at 60 km/h in the same direction, the
relative speed of train B with respect to train A is 20 km/h.
Opposite Direction
When two objects are moving in opposite directions, the relative speed is the sum of their speeds.
Example:
If a train A is moving at 80 km/h and another train B is moving at 60 km/h in the opposite direction, the
relative speed of train B with respect to train A is 140 km/h.
Equations of Relative Motion: Position, Velocity, Acceleration Fixed vs. Moving Reference Frames
A reference frame is a set of coordinates and an origin from which we measure the position of objects.
A fixed reference frame is one that is not accelerating, such as the ground or the stars.
A moving reference frame is one that is accelerating, such as a car or a plane.
• Relative Motion Between Two Particles
Relative motion is the difference in motion between two objects.
To find the relative position of one object with respect to another, subtract the position of the second
object from the position of the first object. Similarly, to find the relative velocity of one object with
respect to another, subtract the velocity of the second object from the velocity of the first object.
The relative acceleration of one object with respect to another is found in the same way as relative
velocity.
It is important to note that the equations of relative motion depend on the choice of reference frame.
