What is Velocity?
Velocity of body is
Distance travelled by body per unit of time in a given direction
Velocity = Distance travelled in a given direction/Time Taken
= Displacement/Time Taken
How is velocity different from speed?
Example 1
Suppose a person travels 6 km in 2 hours towards east
Speed = Distance/Time = 6/2 = 3 km/Hour
Velocity = Displacement/Time = 6/2 = 3 Km/hour towards east
Example 2
A car travels 40 km from Delhi to Noida in half an hour towards east
It comes back from Noida to Delhi in another half an hour
Speed = Distance/Time = 80/1 = 80 km/Hour
Velocity = Displacement/Time = 40  40/1 = 0/1 = 0
Difference between speed and velocity
Speed  Velocity 
It is Distance travelled by body per unit of time 
It is Distance travelled by body per unit of time in a given direction

It only has Magnitude  It has Magnitude as well as direction 
Formula is  Formula is 
Speed =Distance/Time Taken  Velocity =Distance in a given direction/Time Taken 
=Displacement/Time Taken  
Average speed of Moving body is never 0  Average velocity of Moving body can be 0 
Note
Are speed and velocity always equal in Magnitude?
No
They may or may not be equal
Example  Speed and Velocity equal in Magnitude
A car travels 40 km from Delhi to Noida in half an hour towards east
Here Speed = Distance/Time = 40/0.5 = 80 Km/Hour
Velocity = Displacement/Time = 40/0.5 = 80 km/hour towards east
Here ,Magnitude of speed and magnitude of velocity are equal(both are 40)
Example Speed and Velocity not equal in Magnitude
A car travels 40 km from Delhi to Noida in half an hour towards east
It comes back from Noida to Delhi in another half an hour
Speed = Distance/Time = 80/1 = 80 km/Hour
Velocity = Displacement/Time = 40  40/1 = 0/1 = 0
here,Magnitude of speed is 80 but magnitude of velocity is 0
So both are not equal
Summary
Hence,we can say that average speed of moving body can never be 0 but average velocity of moving body can be 0
(ExampleIn case of Round Trip,there is no displacement,so Displacement is 0,so velocity will also be 0)
Questions
Q 1 Page 102  Distinguish between speed and velocity