A65-kg ice skater stands facing a wall with his arms bent and then pushes away from the wall by straightening his arms. at the instant at which his fingers lose contact with the wall, his center of mass has moved 0.55 m , and at this instant he is traveling at 3.5 m/s .

part a: what is the average force exerted by the wall on him? express your answer with the appropriate units. favf a v = 720 n

part b: what is the work done by the wall on him?