Sorry if this is a simple question but I've never done physics before. This just popped into my head at about 11:45 PM: I was playing around with a metal ruler, holding it by a little circle near the end. I was pulling it up and letting it drop because I was bored and had nothing else better to do. I noticed that when I held it at 90 degrees from my computer desk and let it drop. It would swing back 135 degrees from the starting point and come back in the middle at 45 degrees. I did this at different angles: 135 from the desk and 270 from the desk. Each time the 135 would swing back, it would go 180 from the starting point and each time the 270 would swing back it would go 225 from the starting point. And each time it did this it came back to the middle of the starting point and the farthest swing point. Can anybody tell me some type of formula for this? I'm confused on the fact that it always swings back a different angel from the others instead of just going 180. Sorry if this is confusing. Thanks.