Help me to do these Physics Projectiles questions??????Thank you :)?

Question

1. A diver running 1.7 m/s dives out horizontally from the edge of a vertical cliff and 3.0 s later reaches the water below.

How high was the cliff? ... m

How far from its base did the diver hit the water?.... m

2. A ball is thrown horizontally from the roof of a building 52 m tall and lands 45 m from the base. What was the ball's initial speed?

3. A batter hits a fly ball which leaves the bat 0.90 m above the ground at an angle of 57° with an initial speed of 29 m/s heading toward centerfield. Ignore air resistance.

(a) How far from home plate would the ball land if not caught?
(b) The ball is caught by the centerfielder who, starting at a distance of 105 m from home plate, runs straight toward home plate at a constant speed and makes the catch at ground level. Find his speed.

Answer 1

1. Height s(vert) = at^2/2 = 44.145 m
Hor. distance x(hor) = v(hor)t = 5.1 m
2. First need t, then can compute v(hor).
t = sqrt(2s/a) = 3.256 s
v(hor) = x(hor)/t = 13.821 m/s
3. v(vert) = 29*sin(57 deg) = 24.321m/s
s(vert) = v^2/(2a) = 30.149 m; add 0.9 m = 31.049 m
t(up) = v(vert)/a = 2.479 s
t(down) = sqrt(2s(vert)/a) = 2.516 s
t(total) = t(up) + t(down) = 4.995 s
ans a: x(hor) = v(hor) * t = 29cos(57 deg) * t(total) = 78.89 m
ans b: v(cf) = (x(cf) - x(hor)) / t(total) = 5.226 m/s