Science Buddies: "Ask an Expert"

Hi,

I am looking to make a two pan weighing scale that keeps moving. Ideally, I would like to have it move perpetually but I realize that is not going to be possible so I need it move for as long as possible.
How should I go about this?

- Can I use an electromagnet with timer?
- How can I make the fulcrum friction-less?

Please do help !

Thanks

A lot of ideas come to mind, but I'm not certain just what you are trying to accomplish.

In order for a two-pan weighing scale to work it must be in equilibrium, that is, at rest. The unknown mass on the one pan balances the known mass on the other pan and the system is at rest.

Tell me more about why you need it to keep moving?