by on June 13, 2020
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RELATIVE MOTION

When two bodies P and Q are moving  in a straight  line , the motion of P relative to the motion of Q IS called relative Motion.

  1. If P moves with velocity higher than velocity of Q in the same direction along a straight line , the velocity of P relative to velocity of Q is the difference in the velocity of P and Q.
  2. If P moves with velocity higher than or equal to velocity of Q in opposite direction along a straight line , the velocity of P relative to velocity of Q is the addition of the  velocity of P and Q.
  3. If P and Q moves at certain angle to each other the relative velocity is found by adding the velocity of Q reversed to velocity of P using Parallelogram law of vectors.

Example

A car M travelling at  due South of a place K and bus B travelling at  due East of K. What is the velocity of M relative to B ?

 

Solution

   See fig above                                               

 

The direction is the angle which R makes with East

Supposed these vehicles travel in a straight line. What is the velocity of M relative to B ?

  1. If they travel in opposite direction
  2. If they travel in the same direction

 

 

Read more about PHYSICS for High Schools

Posted in: Education
Topics: relative motion
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