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.
Publications Otherpower.com
Wondermagnet.com
Co author of the book "Homebrew Wind Power" ISBN 978-0-9819201-0-8
My articles appear regularly in such magazines as Home Power and Back Home Education/Credentials BA Technical Journalism
Question Does sound travel best through solid, liquid or gas?
Answer Hi Dainelis -- like with many scientific problems, you have to be careful how you ask the question! What do you mean by 'best'? Fastest? Farthest? Loudest?
I'll assume you meant fastest. The speed of sound depends on both the density and the elasticity of the medium it's travelling through. Sounds travels in waves of compression and rarity, so it's fastest in solids because the molecules are packed together more tightly. Sound is next fastest in liquids, again for the same reason. It's slowest in a gas. And, in a gas, the temperature is particularly important--the faster the molecules are moving from heat, the more sound energy they can transfer to their neighbors.
As far as distance travelled --- again, solids and liquids win. However, ther's an additional factor called 'damping' that depends on the elesticity of the medium the sounds waves are travelling through, also scattering. It ends up that lower-frequency sound waves can travel much longer distances than high frequency sounds....this is how whales can communicate over long distances in the ocean--and how elephants do the same in air. Both do their 'long distance' calling with low frequencies.
For more detailed information, see: http://library.thinkquest.org/19537/Physics4.html
and: http://en.wikipedia.org/wiki/Speed_of_sound
