You discover a Cepheid variable star with a 30 day period in the Milky Way. Through careful monitoring for a few years with the Hubble Space Telescope, you determine that it has a parallax of 0.004 arcseconds. How distant is this Cepheid variable star in parsecs?

Arotating space station is said to create “artificial gravity”—a loosely-defined term used for an acceleration that would be crudely similar to gravity. the outer wall of the rotating space station would become a floor for the astronauts, and centripetal acceleration supplied by the floor would allow astronauts to exercise and maintain muscle and bone strength more naturally than in non-rotating space environments. if the space station is 200 m in diameter, what angular velocity would produce an “artificial gravity” of 9.80 m/s^{2} 2 at the rim?

Need only answer if you think you know it

Can anyone plz answer any of these. even if its one it will