Motion

Motion
If a body changes its position with respect to its surrounding it is said to be in motion


Rest 
If a body does not changes its position with respect to its surrounding it is said to be in rest .


Reference Point
The point about which we study the motion of an object is called reference point.


Uniform Motion
If a body travels equal distance in equal interval of time, the body is said to be in uniform motion

Non-Uniform Motion

If a doesnot body travels equal distance in equal interval of time, the body is said to be in non- uniform motion.

Speed
The rate of change of distance per unit time is called speed. 
Speed=Distance travelled
              Time taken 
           = m     
               s    
           = m/s
Therefore, SI Unit of speed is m/s

Velocity

The rate of change of displacement per unit time is called speed. 

Velocity=Dislacement

                 Time taken 

              = m     

                  s    

              = m/s

Therefore, SI Unit of velocity is m/s

Distance Travelled
The length of a path travelled by a moving body in any direction is said to be in distance travelled.Its is a scalar quantity and it has magnitude (having unit) but no direction.It is measured in meter(m) in SI Units.


Displacement
The shortest distance between two points is called displacement.It iis a vector quantity.In SI System Unit of displacement is meter(m).The shortest is always the straight line.  

Difference between mass and weight

Difference between mass and weight

Mass	Weight
The amount of matter contained in a body is called mass.	The force of attraction exerted by Earth to pull an object towards its center is called weight.
It is constant.	It varies from place to place.
It is measured in beam balance.	It is measured in spring balance.