AboutDan Fink Expertise Though my experience is mostly in the fields of electricity, magnetism, and physics, I have a broad science background. My career is in the field of alternative power sources -- solar, wind, water and battery power. But any questions about electricity, magnetism, energy conservation, power generation, electric motors, and even general physics are very welcome--especially from kids. They ask the best questions of all! I pride myself in answering science questions accurately, with ideas for SAFE, easy experiments that kids can perform by themselves--and that let them prove the answers to their own satisfaction. I think science should be fun, and available to everyone, regardless of age.
Experience I have volunteered in our local public schools for 5 years. I currently make presentations at our schools about electricity and magnetism, with a focus on solar, wind, water and other alternative power sources. I try to demonstrate at our schools how easy it is to make electricity, with simple devices using spinning magnets and coils of wire--powered by wind, water, bicycles, gerbils...etc. And of course solar panels! I am the webmaster of Otherpower.com, an alternative energy website. I have lived 10 miles from the nearest power pole for 11 years--I make all my own electricity from scratch with sun, wind and water.
Expert: Dan Fink Date: 2/3/2008 Subject: Egg drop w/ limited materials
Question Hi! My physics class is doing the egg drop competition starting from 6ft, but our materials are very limited. We have the use of 10 cotton balls, a few pipe cleaners, 20 popsicle sticks, rubber bands, paper clips, bendy straws, and elmers glue to hold it all together. Most of the sites I have looked at suggest foam materials, but we can't use these. What do I do?
Answer Hi Cat -- below is pasted in my best advice for the egg drop. But I'm starting to find the problem even more interesting recently! I get egg drop questions here at least once or twice a month. The problem is, the best scientific method is outlined below (using multiple layers of different density foam) has mostly been banned from most recent egg drop competitions, because it works almost every time....the egg survives. You can't make the stress any worse by dropping from a greater height, because the boxes quickly reach terminal velocity due to weight vs. air resistance.
Your 2 goals are: 1) slow the egg down as slowly as possible inside the box when it hits the ground, and 2) distribute the shock over as much surface area of the egg as possible.
SO -- please thoroughly read the info below. It's good info, and it's exactly how the helmet of a bicycle racer or NFL football player protects the wearer's head against shock....different density layers of shock absorbing material that slow your head down as slowly as possible, and distribute the shock over the most surface area. Your skull bones = the egg shell. But in the NFL you are not restricted in the materials you can use in your helmet! I don't think Eli Manning has popsicle sticks in HIS helmet.....
There are all kinds of things you could come up with involving springs made of the rubber bands fastened to the box inside, with paperclips and glue holding them on, with the egg suspended in the middle of the box. Same with bendy straws and paper clips and popcicle sticks. You could make a very elaborate shock absorber with all this stuff....but it will not work all that well. But I suspect that's what your teacher wants you to come up with...some sort of shock absorber.
I do an egg drop about yearly from my 32 foot roof height, just to test the latest info that folks send me....egg drops are a BIG deal at schools.... Your teacher might REALLY not like this design, but it definitely follows the scientific principles outlined above:
Cradle the egg in the cotton balls, tightly! Wrap it with the rubber bands to force the cotton balls tightly against the egg shell. Then wrap the pipe cleaners around this assembly. Take the popsicle sticks and bendy staws and shred them into MULCH with your parent's supervision....they should look like hamster bedding. Pack all of that around your egg+cotton+pipe cleaner package. Anything you have left, pack it into the box around all this. Fluff up those outer layers of shredded poscicle sticks! Use the paperclips and elmers glue for decoration, they are not much use here. Use a small box, so that your mulch is packed tightly in the box...anything that's rattling around will break. Pack it tight with the mulch!
Your teacher might be offended that you took most of the required ingredients and turned them into mulch... but that's science! The 2 principles outlined above will do the trick for you, I hope. If not, or if your teacher is offended, well, all the best scientists had experiments fail too....that's the best opportunity to learn. What I'm advising is to make the limited list of materials you can use into whatever form most closely follows the 2 scientific principles above.
Good luck!
DAN
PS
Here's my best standard egg drop info:
The best solution (I've tried it and it works) is layers of foam of differing density....stiff, closed-cell foam (like from a backpacker's sleeping pad) right around the egg, and layers of foam around that that are less stiff (open-cell foam, like from a couch cushion), completely filling the can. I got this idea from: http://users.adelphia.net/~jberger5/eggdrop.html
which also has lots more information and advice from physicists on this experiment. Be sure to check out that webpage!
The layers of different-density padding make the egg slow down as slowly as possible, and having the egg completely cradled with no gaps ensures the best distribution of force around it's entire shell.
