Shoot the Target!

Description:

The cannon in the animation below is aimed at a 45 degree angle, and points directly at a target suspended 56 m away and 56 m above the cannon. You can set the initial velocity ( in m/s) by typing in a non-zero, positive number.

To fire the gun, click the Fire button. As soon as you fire, the target is released and falls to the ground. (Positions are in meters, time is in seconds. Velocity vectors are shown in blue.)

Question:

At what velocity do you have to fire the cannon in order to hit the falling target? Are there more than 1 possible answers? Explain your answer.