Well let's see.
m/s
27000 km/hour = (27000 km/hr) * (1000m/km] * [1 hour / 3600 sec] = 2700 m/s
miles / hour
27000 km/hour * [1 mile/1.6 km] = 16875 miles / hour (that's fast)
meters / hour
27000 km/hour * 1000 m/km = 27 000 000 m/hour
Miles / Second
27000 km/hour * [1 mile / 1.6km]*[1 hour/3600 sec] = 4.6875 miles / second
Km / second
27000 km/hour [1 hour / 3600 sec] = 7.5 km/second.