Not homework help- looking for ideas.
DD wants to do her project on black holes. We have been reading about them but cannot think of any experiment we can do about the topic.
As an alternative, she would like to make a vacuum with a homemade pump and a mason jar and see how objects (marshmallow, feather donated by Dennis the Duck) act in there.
But she really wants a black hole idea.
?
How about the classic gravity analogy - a big rubber sheet (if you can find such a thing) stretched across the top of a circular frame?
Turn on E!
I always get sucked into that show. Proof that it is a black hole.
Ha- I tried that but she had already been sucked into the black hole of Spongebob and complained mightly. Also demanded (OK- politely requested) a boiled egg.
Since the Big Rubber Sheet[sup]TM[/sup] may be hard to come by, you could use an old cotton one (that you won’t mind permanentally stretching). The trick will be to rig something to hold the sheet tightly around its edges* while something else (like a broom stick handle) pushes down on a spot in the middle. Then get a bunch of marbles and flick them around the indentation. (If you have DD push down with varying pressure, it’s actually a good example for gravity in general.)
I don’t know how much time/inclination you have for this project, but, if it was me, I think I’d try to make an octagon from 1 to 1.5 inch pvc. You should be able to get 45 degree joints and pipe pretty easily from Home Depot/Lowes/etc. You should be able to lay the sheet over the rig, fold, pin, sew. … Rereading this, that’s a lot of work (for a fourth grade project), and not much of the work would be done by DD. I don’t know if I’d really go through with that…
Keep us posted on what you decide, tho.
-geek
Here are some ideas, and here is another, albeit one that it probably well beyond her level.
The problem with “demonstration” projects is that they usually don’t compete well. In the four years I particpated in the regional science fair, the only one where I didn’t get a first was the year I demonstrated different possibilities for hydrogen fusion power generation; although it was probably the one I put the most work into and that looked the prettiest and cost the most (this was waywayback before color laserjet printers made it easy to make a slick-looking presentation on the cheap) it only got a red ribbon. I think I learned more and when into more detail on the science behind fusion and lasers than any other project, but it just didn’t sell well as a project that used the textbook scientific method to do “research”.
I like vacuum jar project, but make sure you try a variety of items that you know will demonstrate some significant and quantifiable effect. Also, be very, very careful with vacuums and glassware; I’d use a heavy-wall pyrex container or a Lexan bottle (like a clear Nalgene bottle) rather than an off-the-shelf Mason jar. You’ll also need a way to measure pressure–a simple water column barometer is easy to improvise and can be interesting as an example of measurement tools itself. And don’t forget to describe all of the safety equipment and procedures in a “Safety” section of the report; a professional-looking final report and well-defined procedures can go a long way to elevating an otherwise unremarkable experiment to a superior entry. (It also teaches your daughter that science is serious and important as well as fun; it’s not all just pretty pictures and Science Guy-type displays.)
Have fun, and good luck with whatever you do.
Stranger
Stupid eggs.
We should devise an experiment to find the best way to boil and peel and egg… :mad:
She’s mulling over the big rubber sheet idea. 
I just wanted to give you kudos for not making a volcano. 
Oh, thanks, Stranger!
Adding a barometer to the vacuum is a great idea and a barometer also a project she did a couple of years ago (she monitored the weather and the home-made barometer daily for over 3 weeks- I was impressed with her dedication to the project!).
I really like the idea of ‘building’ the current project using things learned from previous years.
Last year’s question was “Who has more germs in their mouth, a kid or a dog?” We interviewed people and charted the answers. I was suprised how strongly people debated the question- even the nurses and Doctors at work! We used the stereo reciever for an incubator. I had hoped she would build on that germ growing experiment this year because I enjoyed it so much, but it is her project and she prefers space themes.
So shall I reveal who had more germs, or do you want to discuss first?
Ya, I let them make it at home, but wouldn’t allow it for ‘the project’ even in kindergarten!
I think DS is leaning toward wanting to collect micrometeorites for his project. We could use the big rubber sheet for that, too, if DD choose that project. He likes space themes, too, and we have the microscope.
I love kid science and it gives me lots of reasons to buy stuff like microscopes and chemistry sets.
That sounds like a good idea to me as well.
A few other ideas if she elects to procede with the vacuum jar idea:
[ul]
[li]You’ll need to calibrate the barameter. You can do this by inserting a small round balloon and noting the difference in size as pressure is removed. A simple, back of the envelope calculation (assume the balloon is a sphere to make the math easy) and an application of the ideal gas relation (p[sub]1[/sub]V[sub]1[/sub]=p[sub]2[/sub]V[sub]2[/sub]) will give a good approximation of pressure difference in order to mark or check the scale on the barameter. [/li][li]Try not only objects like a balloon, a feather, or an egg (do this one last, for obvious reasons) but also different chemical substances. See what happens to a small glass of 7-Up or soda water at different fractional pressures. Test what effect vacuum has on different oxidation processes, like burning.[/li][li]Cut up an apple or banana (something that spoils quickly) and see what the difference is in spoilage between a piece in normal atmosphere as opposed to one in a fractional or complete vacuum. [/li][li]Suspend a small speaker or piezoelectric element in the jar and see what the effect of pressure reduction has on sound transmission.[/ul][/li]
I like and would encourage your daughter’s interest in space science; (believe me, we need more female rocket scientists, and anything I can do to settle the balance for future generations is a happy task); unfortunately, it doesn’t lend itself well to experiments on that level, though if she goes on to show interest in mathematics and physics its quite fun to create a computer simulation of the evolution of a star or the formation of a planetary system (moons and rings). This is obviously more advanced, requiring the use of packages like Mathematica or the ability to write somewhat complex code, but not beyond the capability of an enthusiastic and well-advised junior high or high school student.
One of the largest concerns in barfights and the like is bacterial infection due to bites from opponents; there is actually a type of necrotic bacteria that lives (usually benignly) in the human mouth but that can be dangerous when introduced to an open wound. I don’t know whether people have more germs, but you’re more likely to suffer infection from being bitten by, or sharing food and drink with, another person than you are a dog.
Stranger
For a big rubber sheet, you could get a giant latex balloon and cut it in half.
I used to have a source for 80" balloons but their website has disappeared.
You could have her put a toy jet on a treadmill
SHe can build a Tesla coil. I did for a science fair once. Of course, I was in an advanced physics class my senior year, but kids are smarter these days. 
Or, for a simpler approach, she can make a Jacob’s ladder. She just needs some copper pipe and an inverter from a neon sign.
(I had a crazy HS physics teacher. In addition to the above, we would blow up small capacitors by plugging them into a wall socket. Like a fire cracker!)
or, for the more [del]boring[/del] reasonable parent, 30" latex balloons.
Rent the movie Rushmore. Copy the Tidal Wave science fair project. Post pictures.
From a judge’s* perspective:
We are explicitly looking for experiments, not demonstrations. We’re looking for evidence that a) the student did the work themselves, b) the experiment took time (observations over several weeks, or the experiment was repeated several times under varying conditions) and c) the student has given some thought to interpreting the results.
Obviously, the rules may be different at your child’s science fair. It’s entirely possible that you may find the judge’s criteria at the school’s web site. And it’s entirely possible that your child is more interested in following a specific thought than in winning the fair – in which case, good on 'em! Science is supposed to be fun!
*I’ve been a Regional Science Fair judge for years. In this area, schools have their own science fairs and award winners in each grade. The school winners compete against other schools’ winners at the regional science fair.
Thanks Quilter!
I asked her if she could just provide information about black holes, but she said no- it has to be an experiment and not a “cook book” experiment.
I don’t think that would be thick enough. As noted in the catalog, wather balloons break easily.