Answer:
3.97 m/s
Step-by-step explanation:
Speed is defined as the distance covered per unit time. Therefore, s=d÷t=d/t
Where d is distance and t is time
Given distance of 5 km and time of 21 minutes the speed would be given by dividing 5 km by 21 min. However, speed is expressed as km/h or m/s or miles per hour etc. So we nees to get our speed in one of these standard units.
Going for m/s
Conversion
1 km has 1000m hence
5 km=5*1000=5000m
1 min has 60 seconds hence
21 min=21*60=1260 s
Speed=5000m÷1260s=3.9682539682538 m/s
Rounded off, s=3.97 m/s