Question

The speed of a moving car is 20 m/s . Calculate its speed in km/h .Please workout

Answer 1

[1km = 1000m ⇒ 1m = 10⁻³ km
1 hour = 3600s ⇒ 1s = 1 / 3600 h]
m/s ⇒ 1m / 1s ⇒ 10⁻³ km / (1/3600) h
       ⇒ 3600/1000 km/h = 3.6 km/hour = 18/5 km/h
The speed of a moving car = 20 m/s
                                       = 20 x 18/5 km/h
                                       = 72 km/h

Answer 2

A kilometer has 1,000 meters, and an hour has 3,600 seconds, so a kilometer per hour is:
1 km × 1000 m = 1000 km · m


h 1 km h · km Now "cancel out" any units that are both top and bottom: 1000 km · m = 1000 m

h · km h