Calculating Linear Speed of Test Tube in Centrifuge

[mwegimont]

Homework Statement

Find the linear speed of the bottom of a test tube in a centrifuge if the centripetal acceleration there is 5.3×104 times the acceleration of gravity. The distance from the axis of rotation to the bottom of the test tube is 7.3 .

Homework Equations

I have gotten answers of 1900 and 223 m/s.I cannot figure out how to do this problem

 

[Doc Al]

Show how you arrived at those answers. What are the units for the distance? What's the formula for centripetal acceleration?