To convert 3 miles per hour into m/s, first we have to convert miles in to meter and then hour in to second.
As [tex]1 miles = 1.609344 km = 1.609344\times 10^3 m = 1609.3 m[/tex] and[tex]1 hour=60 minutes = 60\times 60= 3600s[/tex]
Therefore,
[tex]3 miles/ h=\frac{3\times1609.3m}{3600s} =1.34 m/s[/tex]