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bio website alanr.xyz
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visits member for 4 years, 7 months
seen 15 hours ago

I studied nuclear engineering primarily in my education, but I also indulged in many tangents such as electric power systems and Japanese. After doing lots of simulation work, I decided I would eventually be mainly a developer and that's what I'm working on now.

My hobbyist interest are many. I like the maker movement, I'm most interested in the sensors and data, the "internet of things" kind of stuff. In physics, I'm probably the most curious about general relativity topics. I've been known to write about climate science when I feel like it. We once had a Nuclear Engineering proposal on Area 51, but it failed.


Aug
27
awarded  Notable Question
Aug
18
comment Rocket thrust over time
"is the thrust in newtons the force per second?" No, the thrust (in Newtons) is the force. To get the change in impulse over a half second, you can multiply the thrust by 0.5 seconds, if this is sufficiently short for your numerical preferences.
Aug
4
revised Is a turbine the same thing as a motor?
technical correctness
Aug
4
answered Is a turbine the same thing as a motor?
Aug
4
comment Surface charge on a straight region of a conductor
Well, there is no gradient along the length of the wire if its the hypothetical infinite example. It will exist for other circumstances, but all of the specifics depend on the situation you're interested in.
Jul
29
comment Calculating the drag force provided by a laminar flow
Restrictions for high numbers? Not likely. Consider atmospheric reentry - projectiles will vaporize before the drag equation loses its validity. This is because the equation is valid for totally ballistic particle collisions. The drag coefficient will change, but that's always dependent on the specific flow pattern anyway. Even when the mean free path is larger than the projectile, it works. Just assume there is just a column of particles in front that bounce off in some constant angle, you get the v^2 form. That's different from the normal application, but it's also strangely the same...
Jul
29
comment Calculating the drag force provided by a laminar flow
The drag model does have such restrictions. It will actually under-estimate the drag for low Reynolds numbers, particularly if it is much less than 1. If you're calculating some transit time for some very small thing, the drag model will give answers which are way off.
Jul
21
comment Could a vacuum airship be possible?
There's no law that says it must be a large monolithic sphere like a hot air balloon. Larger sizes have increasing problems in compression due to buckling. You would, instead, use a large number of tiny vacuum spheres. This would get you the closest to the theoretical limits you've referenced here. At those sizes, you might be able to use electrical charge to balance the crushing pressure, and then you'd surpass the theoretical limits. How to build it is a different story.
Jul
13
revised Size of black hole so large that I could pass event horizon without dying from tidal forces?
typo
Jul
13
answered Size of black hole so large that I could pass event horizon without dying from tidal forces?
Jul
11
answered Calculate pressure with the ideal gas law or $\rho gh$?
Jul
11
revised Grounding a capacitor
grammar
Jul
9
answered Grounding a capacitor
Jun
27
answered Why do two ends of a long conducting wire have the same electric potential?
Jun
13
comment Can lift contradict conservation of energy?
@Chris Yes, that is what I was claiming in very clear terms. Obviously I haven't ran the math, but I suspect that this effect alone can rule out the perpetual motion possibility.
Jun
12
awarded  Nice Answer
Jun
12
answered Can lift contradict conservation of energy?
Jun
1
awarded  Popular Question
May
26
comment How to find set point for PID controller for self balancing robot?
Perhaps hold it upside-down by the wheels and make note of the reading at this point. Then use some math to rotate 180 degrees. It sounds childishly simple but it might work for your issue.
May
25
answered Is Torricelli's law “wrong” for big holes? - Tank draining problem