Solution

A diver comes off a board with arms straight up and legs straight down, giving him a moment of inertia of $18\,\mathrm{kg\,m^{2}}$ about his rotation axis. Then tucks into a small ball, decreasing his moment of inertia to $3.6\,\mathrm{kg\,m^{2}}$. While tucked, he makes two complete rotations in $1.0$ second. If he had not tucked at all, how many revolutions would he have made in $1.5\,\mathrm{s}$ from board to water?