Physics hw due Tom Please Help!?

Question

2. A golf ball rebounds from the floor and travels straight upward with a speed of 5.0 m/s. To what maximum height does the ball rise?

4. ball is thrown vertically up. 8 s later it returns to point on release. wat is the initial velocity?

5. A diver springs upward with an initial speed of 1.8 m/s from a 3.0 m board, Find the velocity with which he strikes the water. What is the highest point he reaches above water?

I ahve these three formulas i keep trying i just dont kno wat to do with the numbers

Answer 1

2) V^2 = 2*g*S
S = 25/(2*9.8) = 1.3(m)
4) The ball reaches the highest point at 4 s. Thus the initial velocity = 4*9.8 = 39 m/s
5) This problem is unsolvable unless this "from a 3.0 m board" is actually "from a board 3m above the water surface". In the later case the final velocity is:
sqrt{(1.8 m/s)^2 + 2*(9.8m/s^2)*(3.0 m)}
= 7.9m/s