I've been trying to find the answer to this question for a*long* time. I think I've finally come to the right place for the answer. Can a smooth ball be thrown so it curves? A lacrosse ball is is basically smooth. There's a small seem where the halves are glued -or melted or whatever and a small logo less than 1mm deep and maybe the size of a nickle or a bit bigger. It weighs between 5 & 5.25 oz. Hypothetically, let's say it's thrown at around 80MPH. When it's thrown, there are three forces: forward movement, gravity & rotation. There's also the Magnus effect, but I'm not sure which side would have the least resistance (and would it always be the same side?) That's about as far as I've gotten. When I say curve, i don't mean like a slow-pitch softball (a rainbow type). I'm referring to like a baseball: left-to-right, or vice versa. I am, in no way, related to physics. I'm a computer geek and a lacrosse coach, so take it easy on my, please If I need to supply more info, please let me know.