A swinging weight that draws looping patterns, like the three shown in red at the top of this page.

Part of this problem is how to design and build the experimental rig you need to draw the patterns in order to investigate them. The trick is to build something. Anything! Then see how well it works and refine it. Don’t wait until your design is perfect on paper. And don’t be put off by the terminology!

Problem in full

This is problem 5 of 17 for IYPT 2027

“Construct a Bowditch pendulum (a pendulum whose strings form a “Y” shape). Investigate how the Lissajous patterns generated by the bob depend on the relevant parameters.”

Specialist equipment

You will need tools and materials to build the frame, the pendulum and a way to record the patterns created. But there is no specification for any of these. Get creative! Use what you have to hand.

Safety First

• Be careful with any tools you use to construct the pendulum, especially power tools.
• Don’t leave tools or the experimental rig where small children can reach them.