(^400) „„„„„ A Textbook of Engineering Mechanics
400

Relative Velocity 19

CHAPTERCHAPTERCHAPTERCHAPTERCHAPTER

Contents

1. Introduction.


2. Methods for Relative
   Velocity.


3. Relative velocity of Rain
   and Man.


4. Relative Velocity of Two
   Bodies Moving Along
   Inclined Directions.


5. Least Distance Between
   Two Bodies Moving Along
   Inclined Directions.


6. Time for Exchange of
   Signals of Two Bodies
   Moving Along Inclined
   Directions.

19.1. INTRODUCTION

It has been established since long that every

motion is relative, as an absolute motion is impossible

to conceive. Strictly speaking, our motion is always

relative with reference to the Earth , which is supposed

to be fixed or at rest. But we know that our Earth is

also not at rest. It has some relative velocity with

respect to the celestial bodies such as sun, moon etc.

These celestial bodies, in turn, have some relative

velocity with respect to the stars of the universe.

It will be interesting to know that when we say

that a train is moving at 50 kilometres per hour, we

simply mean that the speed of the train, which appears