A cord is wrapped around the rim of a solid uniform wheel 0.300 {\rm m} in radius and of mass 9.00 {\rm kg}. A stable horizontal pull of 42.0 {\rm N} to the right is exerted on the cord, pulling it off tangentially from the wheel. The wheel is mounted on frictionless bearings on a horizontal axle during its center. Calculate the angular acceleration of the wheel in rad/s^2.