The velocity of car is 80.0 miles per hour. What is the velocity of car in meters per second? (1 km - 0.621 miles) m/s

80 miles per hour = 35.7632 meters per second.

(divide the speed by 2.237)

First of all, you haven't said anything about what direction the car is going, so we're only talking about speed here, not velocity.

Take these two fractions: (1 hour/3600 sec) and (1000 meter/0.621 mile)

Each of those fractions is exactly equal to ' 1 ', because it has the exact same thing on top and bottom. So I can multiply any quantity by them, without changing the value of the quantity, only the units.

I'm going to take your 80 mile/hour, multiply it by those 2 fractions, then simplify everything:

Speed = (80 mile/hour) x (1 hour/3600 sec) x (1,000 meter/0.621 mile)

Speed = (80·1·1000 / (1·3600·0.621) (mile-hour-meter/hour-sec-mile)

Speed = (80,000 / 2235.6) (meter / sec)

Speed = 35.78 meters per second