373 reputation
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bio website blueraja.com/blog
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visits member for 4 years, 1 month
seen Dec 19 at 17:31

Sep
9
awarded  Citizen Patrol
Sep
5
awarded  Famous Question
Aug
23
comment Why is gravitational potential energy negative, and what does that mean?
This question is about potential energy, not acceleration vectors...
Aug
13
comment Are there two theories that are mathematically identical but ontologically different?
This isn't quite the same. These are different physical interpretations of the same mathematical theories, not two mathematical theories based on different physical observations but leading to the same results. The difference is that the math came first, then the differing interpretations, not the other way around.
Jul
9
comment How effective is speeding?
"it costs you an additional $1.50 an hour to go 5 mph over the speed limit" - That depends on the speed-limit... Also, cost-per-hour is a complete red-herring, what's important is cost-per-mile. No one goes out and drives for a specific time, they drive a specific distance. -1
Jun
17
comment Voltage and Current in transformers
I wrote a blog post about this a few years ago: blueraja.com/blog/194/do-transformers-obey-ohms-law
May
16
comment Integral equations contradict The Uncertainty Principle?
@Lucas Integrals are a mathematical tool, they're not inherently classical or quantum, and in fact are used extensively in both theories. So it's more like, in classical mechanics, integrals allow you to determine the position of a particle over time given its velocity-graph. They cannot be used in QM for that same purpose (due to the uncertainty principle), but they are used for many other calculations.
Apr
21
comment Birds sitting on electric wires: potential difference between the legs
This is only half the answer. The danger with the high-voltage "transmission" lines that span between cities is the current that would flow due to the bird's capacitance, not parallel-resistance. When the bird lands, its potential must equalize the power-line's, which for a 700kV line, could mean a large shock. It's basically a static-shock, but lasts longer due to the large capacitance of the power plant. It's a huge danger for electrical-line workers. To my knowledge, this shock should happen and could indeed kill a bird.
Feb
10
awarded  Custodian
Feb
10
reviewed Reject Why is gravitational potential energy negative, and what does that mean?
Feb
10
awarded  Popular Question
Nov
26
comment Some doubts about photons
This answer claims that light moves faster than the speed of light. That's very confusing.
Nov
20
comment Why don't metals bond when touched together?
There is a serious lack of videos about this on Youtube
Oct
31
comment Why does this perpetuum mobile not work?(Gases and Densities)
Is "perpetuum mobile" a common term for perpetual motion machine? I'd never heard of it before, and the wikipedia article is about music.
Oct
2
comment If I am travelling on a car at around 60 km/h, and I shine a light, does that mean that the light is travelling faster than the speed of light?
This is exactly the question Einstein asked, which led him to discover special relativity.
Sep
20
revised Does alternating current (AC) require a complete circuit?
Added a link
Sep
20
suggested approved edit on Does alternating current (AC) require a complete circuit?
Sep
20
accepted Does alternating current (AC) require a complete circuit?
Sep
9
comment Are the air particles in today's wind on earth (more or less) the same as the air 2/3 billion years ago?
@user80551: It was a guesstimate. But even using, say, 10^18 molecules, pari/gp tells me there are still around 6800 $9$'s after the decimal.
Sep
9
comment Are the air particles in today's wind on earth (more or less) the same as the air 2/3 billion years ago?
"so the probability that a particular oxygen molecule hitting your face is [..] $\approx 1.58 \times 10^{-14}$, ie. basically 0" - Except that the number of molocules that hit your face in a second is somewhere on the order of $10^{23}$, which means that the probability that one of these atoms existed that long ago is $1-(1-1.58 \times 10^{-14})^{10^{23}} \approx 99.99999999999...\%$