after b was moved the tension would have been divided by 2 because F=ma, leading to T+T-250N = 0, so t equalled 125 N i guess. I kinda remember question 6 now, which was easy enough when treating vertical and horizontal components separetely. I think i got t to be 0.89 because u had a quadratic there involving 4.9t^2 something. You had to use the quadratic formula (or a graphic calc. but i didnt have one) to work out t and then like someone else said put that into the s=12t you worked out earlier on.