THE SLOW AND THE SPEEDY. As being an inquisitive engineer geek, I picked up a dozen of broken balls and measured the thickness on the outer shell. Balls with a thinner shell proved to rotate faster, as is expected.
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WHY DO ABS BALLS SPINNING AT LOW RATE.The most apparent dissimilarity between balls of celluloid material and the ABS material is the rotation speed, and the celluloid is more spinny by general notion of players/ Why so?
The two materials are known to differ in density significantly. 1.1 g/cm³ ABS plastic vs 1.45 g/cm³ nitrozo celluloid. This is the very factor to cause the balls having different shell thickness. The celluloid balls will get much thinner shell compared to ABS, which can be verified by a simple household instrument.
According to the general laws of Mechanics, a sphere with a thick outer shell (=ABS material) will have a low spin rate.
Be happy.