To solve this problem, we must remember that momentum is always conserved. In this case, we use the angular momentum L: L = m v r Where, L = angular momentum m = mass v = angular velocity r = radius Since L1 = L2 and m1 = m2, therefore: v1 r2 = v2 r2 (8 m / s) (10 cm) = v2 (30 cm) v2 = 2.67 m / s
A spinning spherical shell with radius 30 cm and negligent mass is filled with 0.5kg of sand. It started spinning at an angular velocity of 8 m/s. All the sand starts within the center 10-cm and by the end has moved to the outermost radius. What is its new angular velocity?