A group of kids is launching water balloons from a hillside with a water balloon slingshot. When the balloons are launched they start from a height of 31 m above the final position and hit the ground with a final speed of 51 m/s.

Required:
a. Why does the balloon always hit the ground with the same speed regardless of the angle of launch?
b. What is the initial speed of the balloon when it leaves the slingshot?