Question

A water balloon slingshot launches its projectiles essentially from ground level at a speed of 25.5 m/s . (You can ignore air resistance.)
A: At what angle should the slingshot be aimed to achieve its maximum range?

B: If shot at the angle you calculated in Part A, how far will a water balloon travel horizontally?

C: For how long will the balloon be in the air?

Answer 1

The formulae for range and flight time for a given launch from ground level at angle θ are
R=v2sin2θg
and
T=2vsinθg

these follow from the equations of motion and the parabolic/symmetric shape of flight without air resiatance you can see that you will max out on range at

θ=45o