Science Experiments

Question: Science Fair projects?!?!?

My little sister is looking for a project for her science fair. She thinks she wants to do something with physics (specifically, forces), but can’t find a good one. The guidelines:
-must be experiment (w/ hypothesis), not DEMONstration (i.e. volcano or solar system model)
-must be useful to people or to science
-must be at appropriate level of difficulty (she is in 7th grade)
-must be fairly unique (not previously done)

We’d appreciate ANY ideas you have for us. Thanks!

Answer: Here i got one of some ideas that i used when i was at 7th, long, long ago…..
Why don’t you try something with magnets, and the effect on certain metals like iron and nickel, and why they don’t work on others like copper? You can find info on any elementary physics book. One good suggestion is to work on a petri box with drops of mercury in which you put an electrical charge with a cable connected to a battery terminals(just avoid to touch them) and see how it’s atracted or rejected by any of both poles of the battery.

!!!Solar System Formation!!!