It has been suggested that cylinders rotating about their long axis with dimensions 19 km long and 6.9 km in diameter be placed in space and used as colonies. What angular speed must such a cylinder have so that the centripetal acceleration at its surface equals the free-fall acceleration on Earth?

r omega^2 = 9.81 m/s^2

r = (6.9/2)*1000 = 3450 m

so
omega^2 = 9.81/3450

omega = .0533 radians/s

(that is about 118 seconds /revolution or about 2 minutes per revolution)