1) Average speed
First of all, we need to convert the total time from minutes to seconds. Keeping in mind that 1 min = 60 s, we have
[tex] t=14.9 min \cdot 60 s/min =894 s [/tex]
Each lap is 400 m, and the person completes 8 laps, so the total distance covered by the person is
[tex] S=8 \cdot 400 m=3200 m [/tex]
The average speed is just the ratio between the total distance and the total time:
[tex] v=\frac{S}{t}=\frac{3200 m}{894 s}=3.6 m/s [/tex]
2) Average velocity
The average velocity is equal to the ratio between the total displacement of the person and the total time:
[tex] v=\frac{d}{t} [/tex]
however, the total displacement is zero, because the person returns to his starting point (the track is a closed circuit). Therefore, d=0 and the average velocity is zero as well:
[tex] v=0 [/tex]
