From: RoyMayeda@aol.com
Date: Wed Dec 06 2000 - 05:50:28 PST
From: RoyMayeda@aol.com Message-ID: <a7.9ad3545.275f9e24@aol.com> Date: Wed, 6 Dec 2000 08:50:28 EST Subject: Re: Student questions...
I'll take a shot at some of this, aided by an old CRC reference.
1) It depends. The density is affected by the temperature, pressure, and
humidity of the atmosphere at the time. At "normal" pressure and temperature
(1 atm., 20-25°C), moist air is about 1.2 g/L.
2) N2=78.084%, O2=20.946, Ar=0.934%, CO2=0.033%, Ne=18ppm,He=5ppm, CH4=2ppm,
Kr=1ppm, H2=0.5ppm, N2O=0.5ppm, Xe=0.1ppm
3) Objects of the same density as water will be "neutrally buoyant" and
retain their elevation in a water column. If a fish or submarine is holding
its depth without any thrust, it has reached this density.
4) Well, no. Energy has a mass equivalent (E=mc^2), but energy is not
matter. Sound is essentially the organized motion of matter. We describe
light as having particulate properties, but again, it is energy.
5) Far as I've heard, yes, quarks are still the most basic. (Not that I've
been looking at much on particle research!)
"It is better to remain silent and have people think you a fool, than to
speak and remove all doubt"... oops! :-)
Roy Mayeda
Valley HS, Sacramento CA
This archive was generated by hypermail 2b29 : Tue Oct 16 2001 - 12:22:04 PDT