Build a Catapult to Shoot a Ball 2m into a Bucket

[ConsistentX]

we were given a project in physics where you build a catapult that shoots a tennis ball 2, 4, or 6m. Now i have a basic design that I am not sure if it will shoot 2m. all i need is the ball to be able to shoot 2m into a 5 gallon bucket.
here is the design i am loooking at:
http://www.stormthecastle.com/catapult/catapult-assembly1.htm

Also. if i decrease the stopping point of the catapult will that increase the distance?

 

[burtonlang]

Does it have to be a catapult, or can it be a trebuchet? Trebuchet's are much easier to build, generally.