Expert: Jayendra Upadhye - 3/8/2008

Question
My 7 yrs old is going to discuss the Planets at her elementary school science fair. I thought it would be fun to take a different approach. Is there a simple way she can demonstrate how a planet is formed? If so what do we need? Thank you.

Answer
Hi,
I found this very interesting question in the question pool, and am answering it right away.
I do not know in which country you reside, and so can not make any guess with regard to what apparatus your girl may have access to in the laboratory.

However, the beauty of science is that if we use our minds, we can always "make do" with powerful analogies and simple apparatus, (the paper & pen as the last resort is always there..).

You see, (explain this to her too),
1 - Gravitation is a point field.
2 - And it is "conservative", meaning one expends energy while working against it, and "gets that energy back" when one allows gravity to "do the work".
This is the "work energy" theorem.
In conservative fields, the amount of work done "against the field" is stored within the body as potential energy, and given back when a body falls from a hieght, as its kinetic energy.
3 - An Electrostatic field is also like a gravitational field, only much stronger. (gravity is a weak force and considered as such by physicists),

So much for the theory.
Now for the "trick" part.

Have a glass beaker full of light plastic "fluff".
Make the fluff by cutting and recutting a plastic bag into pieces as small as you are able to. (pass and repass thru a shredder if you can do such a thing..:).

Have a "magic glass" (or ebonite) wand and woollend gloves ready.

Charge the galss wand by rubbing it vigorously with the wool.

All she then needs to do is "say the above theory", as cooly as she can, and point out how an electrostatic field can mimic a gravitational field much better, and "DIP THE WAND IN THE BEAKER"!
Taking care not to insert it into the fluff, but holding it some distance above.

If the childern attendingh are really young, they will scream in joy when they find the fluff "gravitating" to the tip of the wand!

She must say.."LIKE THIS, gravity attracts smaller pieces of matter together over time, to form much larger bodies! (point the clump of sticking fluff).

Period!
Qed etc!

[OH Yes! Like all magicians, do practise! It will only make one perfect!!]

regards

Please do rate the answer.

Jayen