1. The problem statement, all variables and given/known data there's an image of the situation 2. Relevant equations F= mω^2 R 3. The attempt at a solution so, in the image there are two spheres that exerts a tension on the string using their centrifugal, since the centrifugal bodies are two I expect that the tension is the sum in intensity of the two forces, do you agree? Another question is: why the centrifugal forces acts to the string? Aren't these forces supposed to act just on the spheres?