A baseball just clears a 3.0m tall wall positioned 120m from home plate. If the ball left the bat 1.2 m above the ground at an angle of 45 degrees above the horizontal, how fast was it going when it left the bat.

Answer 1

hfinal=hinitial+vsintheta*timeinair-4.9time^2

so,you have everything except timeinair.

Look at the horizontal equation:
120=vcosTheta*time

solve this for time in terms of v . THEn put it in the first equation, leaving a quadratic in terms of v.
solve for v, using the quadratic equation.