Kilometers per second (km/s)
Kilometers per second (km/s) is a unit of speed that measures the number of kilometers traveled in one second. It is occasionally used in astronomy and astrophysics where large distances are involved.
Miles per hour (mph, mi/h)
Miles per hour (mph or mi/h) is the number of miles covered in one hour. It is the unit for road speeds in the United States and the United Kingdom, and 1 mph is exactly 0.44704 meters per second.