The figure shows all the forces acting on a $2.0\mathrm{kg}$ solid disk of diameter $4.0\mathrm{cm}$. What is the magnitude of the disk's angular acceleration?

A 70.0-kg person stands on a tiny rotating platform with arms outstretched.

(a) Estimate the moment of inertia of the person using the following approximations: the body (including head and legs) is a 62.0-kg cylinder, 16 cm in radius and 1.70 m high; and each arm is a 4.0-kg thin rod, 60.0 cm long, attached to the cylinder.

A system is made of two small masses (M_LEFT = 3 kg, M_RIGHT = 4 kg) attached to the ends of a 5 kg, 2-m long thin rod, as shown. Calculate the moment of inertia of the system if it spins about a perpendicular axis through the mass on the left.

A solid disc 4 m in diameter has a moment of inertia equal to 30 kg m² about an axis through the disc, perpendicular to its face. The disc spins at a constant 120 RPM. Calculate the mass of the disc.