Examples with explanations on the concepts of average speed and average velocity of moving object. More problems and their solutions can be found in this website.
The average speed is a scalar quantity (magnitude) that describes the rate of change (with the time) of the distance of a moving object.
average speed = 
distance
time

The average velocity is a vector quantity (magnitude and direction) that describes the rate of change (with the time) of the position of a moving object.
average velocity = 
change in position
time

= 
displacement
time

An object moves from A to D along the red path as shown below in 41 minutes and 40 seconds.
a) Find the average speed of the object in m/s
b) Find the average velocity of the object in m/s
average speed = 
distance
time

= 
9 km
41 mn + 40 s

= 
9000 m
(41*60 + 40) s

= 
9000 m
2500 s

= 3.6 m/s 
average velocity = 
displacement
time

= 
5 km
41 mn + 40 s

= 
5000 m
2500 s

= 2.5 m/s 
The average velocity is a vector whose magnitude is 2.5 m/s and its direction is to the east.
An object moves, along a line, from point A to B to C and then back to B again as shown in the figure below in half an hour.
a) Find the average speed of the moving object in km/h.
b) Find the magnitude of the average velocity of the object in km/h.
Solution:
average speed = 
distance
time

= 
13 km
0.5 hour

= 26 km/h 
average velocity = 
displacement
time

= 
5 km
0.5 hour

= 10 km/h 
An fast object moves from point A to B to C to D and then back to A along the rectangle shown in the figure below in 5 seconds.
a) Find the average speed of the moving object in m/s.
b) Find the velocity of the object in m/s.
average speed = 
distance
time

= 
16 km
5 seconds

= 
16000 m
5 seconds

= 3200 m/s 
average velocity = 
displacement
time

= 
0
5 second

= 0 
A person walks, for two hours, from point A to B to C along a circular field as shown in the figure below.
a) Find the average speed of the person in km/h.
b) Find the velocity of the person.
average speed = 
distance
time

= 
3 Pi km
2 hours

= 1.5 Pi km/h = 4.7 km/h 
average velocity = 
displacement
time

= 
6 km
2 hours

= 3 km/h 
average speed = 
distance
time

= 
1.5 Pi km
1 hour + 12 minutes

= 
1.5 Pi km
1 hour + 12/60 hour

= 
1.5 Pi km
1.2 hour

average velocity = 
displacement
time

= 
3√2 km
1 hour + 12 minutes

= 
3√2 km
1.2 hours
