Hi, I was hoping I could get some help on these problems. Here's the first problem: 1. A projected space station consists of a circular tube that is set rotating about its center (like a tubular bicycle tire). The circle formed by the tube has a diameter of about D = 1.30km. What must be the rotation speed (in revolutions per day) if an effect equal to gravity at the surface of the Earth (1g) is to be felt? So here's what I did: I converted the diameter from km to m, then got the radius, which is 650 km. Then, I found the velocity of the station by doing v= sqrt r x g . I got 79.81 m/s. And then I used the formula T= 2PiR/V ....and I got 51.17. My question would be what are the units at this point? I assumed it was revolutions per second, then converted to revolutions per day, but that was not correct. Maybe I'm missing a step, so please help!