Kelly doll? how to make it balanced? Physics?

Question

Hi guys were making a project for physics class. We are currently discussing about law of inertia. Now our task is to make a kelly doll. To be more precise here's an example: A punching bag which you hit it and will come back to you... Something like that. So how do I make it? Any steps?

Answer 1

I think you are referring to a 'doll' that has a low center of gravity.
In a rough it is a rod or a wooden dowel of about 4-6 feet in length that has a parabolic surface attached with some considerable mass of say 30-50 lb. The rest is up to your imagination.

Answer 2

Kelly Doll Bag