What are the principles of physics behind the medieval weapon, ballista ?

Pika Bear: What are the principles of physics behind the medieval weapon, ballista ?
What are the principles of physics behind the medieval weapon, ballista ?

How is it operated >?

Answers and Views:

Answer by Kat Grl
What a neat weapon. make a good potato launcher.
good picture here
https://en.wikipedia.org/wiki/Ballista