If we assume the 6.5kg fidget spinner is a solid disc of uniform density, with a moment of inertia 0.66 kgm2

Question

The moment of inertia of a solid disc is I=(0.5)mR²

what is the radius of the object in cm to 2s.f? 

Answer 1

Given I = 0.5 m*r²

I =0.66 Kg m²

m = 6.5 kg

r² = 0.5 / 6.5 =5/65

r= 1/√ 13 m

r= 100/√ 13 cm