Joseph jogs from one end A to the other end B of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point C in another 1 minute. What are Joseph’s average speeds and velocities in jogging?
(a) From A to B
(b) From A to C
Firstly, we have to draw a line segment to show the movement of Joseph during his jogging:
(a) Given,
Total distance from A to B = 300 m
Total time taken = 2 minutes 30 seconds
= 2 × 60 + 30
= 120 + 30
= 150 s
Average speed (from A to B) =
=
= 2.0 m/s (i)
The displacement and the time taken of Joseph is same ingoing from A to B i.e., 300m and 150 s respectively.
Therefore, Average velocity (from A to B) =
= 
= 2.0 m/s (ii)
So, from (i) and (ii) it is clear that the average speed and average velocity of Joseph during his jogging is same.
(b) Given,
Total distance from A to C = 300 + 100
= 400 m
Total time = 2 minutes 20 seconds + 1 minutes
= 150 s + 60 s
= 210 s
Average Speed (from A to C) = 
= 
= 1.90 m/s (iii)
Now the average velocity of Joseph from A to C:
Displacement = 300 – 100
= 200 m
Total time taken is same as that of the time taken from A to C i.e., 210 s
Average velocity (from A to C) =
= 
= 0.95 m/s (iv)
From (iii) and (iv) it is clear that the average speed of Joseph is different from his average his velocity.