For a small solid sphere, cylinder or disk, I came up with the maximum rev/s that such an object could be spun as:

w = [2p/(dr^2)]^(1/2)

where:

p = ultimate tensile strength d = density r = radius

As an example, for a diamond disk 1 cm in radius...

p = 90 GPa d = 3520 kg/m^3 r = 0.01 m

w = 720,000 /s

This corresponds to a surface velocity of 45 km/s. Empirically this is within the right ballpark, but I suspect the constant '2' is wrong. Does anyone know where I can find the correct formula?

Also, is there a concise way to describe the 'obvious' axis to spin a cylinder or disk? (e.g. the way a top spins)

Thanks for reading,

Russell