Engineering homework help

A playground merry-go-round has a radius of 4.60 {rm m} and a moment of inertia of 250 kg m^2 and turns with negligible friction about a vertical axle through its center.A child applies a 25.0 N force tangentially to the edge of the merry-go-round for 20.0 s. If the merry-go-round is initially at rest, what is its angular velocity after this 20.0 s interval?