1,749 reputation
715
bio website markbeadles.com
location Columbus, OH
age 47
visits member for 3 years
seen Jan 28 '13 at 17:55

Jan
19
comment How does placing objects in liquids affect the mass?
Also - scales always measure weight. They work by measuring the force that gravity applies to the object.
Jan
15
comment Doppler's effect use
here is an example from Microsoft of the use of Doppler pitch shifting to simulate objects moving toward or away from the player.
Jan
15
comment Doppler's effect use
Yes, and Doppler sonography is also used for imaging of other organs to determine the various blood flows into and out of them, not just the heart: brain, liver, kidney, really pretty much anything. It's a fantastic technology that has saved or improved many lives by eliminating the need for exploratory surgery, and allowing necessary surgeries to be much more targeted.
Jan
14
comment Can a big microwave used to dry clothes?
If by "cool" you mean "catches your Levi's on fire", then yeah. :)
Jan
13
comment How does lifting an object effect its entropy
Again, as the gas of photons streams down into the box that is lower in the gravity well, its temperature and $\therefore$ entropy will increase. The Baez page really has some good thoughts on an almost identical problem.
Jan
13
comment How does lifting an object effect its entropy
Also see this related question on gravity vs entropy and this thought experiment on John Baez' site. In particular, wouldnt' some of the photons escape the gravitational well in 2?
Jan
13
comment How does lifting an object effect its entropy
But wouldn't the temperature of the photon gas increase as it falls in the gravity field, thus increasing the entropy during step 3?
Jan
5
comment How to distinguish female and male voices via Fourier analysis?
Note that the human ear works by means of what is essentially a mechanically-performed spectral analysis via something like a continuous wavelet transform. Did a paper on this for neurolinguistics once :)
Jan
5
comment How to distinguish female and male voices via Fourier analysis?
Yes, they are used extensively in looking vocal dysfunction as well. a google search for "formants vocal dysfunction" is quite revealing!
Jan
5
comment How to distinguish female and male voices via Fourier analysis?
"Formant dispersion" is a term of art in the field of auditory acoustics/linguistics. Formants are a key concept there. Formants are the spectral peaks of the voice sound, see en.wikipedia.org/wiki/Formant. In linguistics they're used to characterize and distinguish vowel and other continuant sounds and to analyze consonants by their impact on adjacent formants.
Jan
5
comment Volume of Matter in the Universe
Except of course, if you do the calculation you suggest, you'll find that $2GM/c^2 =2G(1.5 \times 10^{53})kg/c^2 = 2 \times 10^{26}m $, just about the radius of the observable universe. The universe is already just about the same density as a black hole of equivalent radius. this doesn't make the universe a black hole but it does make this question a bit intractable.
Jan
4
comment Does the measured mass of earth include that of the atmosphere?
you have an error in the sign of your exponent of the atmosphere's mass.
Jan
3
comment Is one way glass possible?
@MarkEichenlaub In your scenario, the remarkable part is the zero conduction mechanism, not the one-way glass.
Dec
30
comment Why does Venus rotate the opposite direction as other planets?
The leading theory for the Moon's formation is a planet-sized body colliding with Earth, yet the Earth is manifestly spherical and this doesn't pose a problem. Given time a large-enough body will settle back into a sphere. It's certainly possible for Venus to have been struck and yet still be a sphere. Given a large-enough impact the entire surface would liquefy, therefore the "same degree of aging" would be found all over. Finally, venus has more volcanoes than any other planet wiki
Dec
23
comment Puzzled by $\mathrm p = -i\hbar \nabla = m \dot{\mathrm r}$?
Ah, gotcha. Thanks @RonMaimon
Dec
18
comment Rotate a long bar in space and get close to (or even beyond) the speed of light $c$
Your assumption of "all the practicalities working" is far too big of an assumption; you're assuming away the very heart of the question, which is: can I do this using a rigid body.
Dec
15
comment What is reason for electronic compass calibration
@JanHudec True, the 3rd dimension is not interesting in compass applications, but the Hall effect unit does measure all 3 vectors.
Dec
14
comment What is reason for electronic compass calibration
@Georg I operated communications systems including field phones int he Army once myself. Calling a TA-312 and an iPhone both a "telephone" is like calling both a chihuahua and a great dane a "dog" ;)
Dec
14
comment What is reason for electronic compass calibration
@BenCrowell and JanHudec as I understand it from the video I added above, the trick is that the "figure 8" is actually a move that takes it through all three dimensions. This would allow the on-board logic to make a good educated guess about which vectors belong to which orientation based on their relative strength.
Dec
14
comment How do physicists justify using $c^2$ in equations?
Wikipedia:Mass–energy equivalence gives a pretty good description of the history behind the mysterious c squared.