You could build a catapult out of arrows and bungee cords. Set the stopping point at some angle. Then calculate expected velocity, kinetetic energy, etc... Maybe the angular velocity, momentum etc... of the swining arm...possibly coefficient of friction, stuff like that.
Welcome to PF, Jstark11. It would probably be to your advantage to choose a subject that you enjoy and pick an experiment that is within that area. What are your interests?
How about you take two pots, one wider than the other, and fill them with the same amount of water (making sure the water's all at the same temp.) Put a pot on a burner and heat it up until it boils; every minute or so record the temperature with an oven thermometer or something. Do the same with the other pot some time later in the day (after the burner's cooled down). See if the dimensions of the pots have anything to do with how quickly the water heats up.