A dad pushes tangentially on a small hand-driven merry-go-round and is able to accelerate it from rest to a frequency of 18 rpm in 12.0 s. Assume the merry-go-round is a uniform disk of radius 2.7 m and has a mass of 780 kg , and two children (each with a mass of 21 kg ) sit opposite each other on the edge. Calculate the torque required to produce the acceleration, neglecting frictional torque. What force is required at the edge?