2 centripetal acceleration problems

[kcskcskcsyes]

Any help would be greatly appreciated...

It has been suggested that rotating cylinders about 10 mi long and 5.0 mi 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?

An air puch of mass 0.25 kg is tied to a string and allowed to revolve in a circle of radius 1.0 m on a frictionless horizontal table. The other end of the string passes through a hole in the center of the table, and a mass of 1.0 kg is tied to it. The suspended mass remains in equilibrium while the puck on the tabletop revolves. a) What is the tension in the string? b) What is the horizontal force acting on the puck? c) What is the speed of the puck?

 

[drpizza]

First, you need to show us what you've attempted so far on these problems. What formulas do you know?

 

[kcskcskcsyes]

um i think on the first one you use the a=v2/r equation
is that correct?