1. The angular velocity of the disk is omega(disk) = 0.0462 rad/sec 2. The angular momemtum of the disk (which has mass M = 5321 kg) is L(disk) = 768 kg*m^2/s 3. Joe's angular momentum around the center of the disk must be equal and opposite: L(disk) + L(Joe) = 0 L(Joe) = -L(disk) = -768 kg*m^2/s 4. Joe's mass is 60 kg, and his distance from the center of the disk is R = 2.5 meters. We can compute his moment of inertia around the center of the disk: I(Joe) = m(Joe)*R*R = 1500 kg*m^2 We can now compute Joe's angular velocity: L(Joe) = I(Joe) * omega(Joe) L(Joe) -768 kg*m^2/s --> omega(Joe) = ---------- = ------------------ I(Joe) 1500 kg*m^2 omega(Joe) = 0.511 rad/s 5. How fast is Joe moving? His angular velocity relative to that of the disk is omega_diff = omega(Joe) - omega(disk) = -0.556 rad/sec so the magnitude of the linear speed of his feet, relative to the disk, is speed = abs(omega_diff*R) = 1.39 m/s