1km=1000m
1h=60min
60\frac{km}{h}=60*\frac{1000m}{60min}=1000\frac{m}{min}
1h=3600s
60\frac{km}{h}=60*\frac{1000m}{3600s}=\frac{1000}{60}\frac{m}{s}=\frac{50}{3}=16\frac{2}{3}\frac{m}{s}
------------------
1h=3600s
1s=\frac{1}{3600}h
1m=0,001km
5\frac{m}{s}=5*\frac{0,001km}{\frac{1}{3600}h}=5*\frac{1}{1000}*\frac{3600}{1}\frac{km}{h}=5*3,6=18\frac{km}{h}