1M rpm, circumference about ½ m ⇒ ≈500,000 m/minute = 30,000 km/hour ≈ Mach 25 (at its widest point) That’s very fast, indeed. It wouldn’t surprise me if that

1M rpm, circumference about ½ m ⇒ ≈500,000 m/minute = 30,000 km/hour ≈ Mach 25 (at its widest point) That’s very fast, indeed. It wouldn’t surprise me if that ball would partly melt, if it wouldn’t be torn apart by centrifugal forces first.