6b: impulse is change in momentum. Change in momentum p=m[v(final)-v(initial). Final velocity is zero and initial velocity is the one you calculated before impact: -15.7 since it’s going down. Now plug in numbers and you get 78.5 in the upward direction.
6c: change in momentum p=Ft. we already calculated change in momentum. So plug it into equation and solve for t. 78.5/655= 0.119 s
Apply the same idea for question 7. Hope this helped