Vansig

i have 12 microseconds to heat 1 kg of air from 240 kelvin to its dissociation temperature.

if i hit it with a coherent IR beam at the strong oxygen absorption line near 4.5 THz,

how much power will i need?

A search reveals some popular articles, but no release schedule as far as i know. As of April, this year, there were blogs about it being released this year, but it is now December, so what is the present status?

"Our goal for Bloom is that it grow into a generally-useful, open-source language environment for distributed programming. We hope to release an initial version of Bloom and its runtime late this year. (Academic researchers are notoriously bad at predicting ship dates, so check back frequently. That said, our research team has clocked a lot of hours building both commercial and open-source software, and we do take pride in building real things.)"

-- http://databeta.wordpress.com/2010/04/23/tr10-bloo...

here is just one, of perhaps hundreds of stars that are within the zone of probable origins for the Wow! signal. which of them are within 50 light years, that have planets?

http://www.google.com/sky/#latitude=-27.2024269224...

for reference,

http://en.wikipedia.org/wiki/Wow!_signal

A bifilar, barrel toroid transformer is wound with insulated, 26 awg speaker wire, on a toilet paper roll form. it consists of 2x 40 turns, and measures ~1 ohm resistance across matching pairs of legs. Each loop is long, and narrow, consuming 20cm of wire per turn, and there are 3 turns per cm.

an alpha particle (moving point-charge, q = +2e), travels through the coil's axis at .08 c; calculate the induced voltage and currents in the coil, and the force on q.

what free tools let me model this coil, and visualize and animate the fields and forces?

a 30V rated capacitor is charged to 5.00 V, and found to contain 1.2 joules of energy.

what is the capacitance?

helium is chosen as the primary coolant for a fusion reactor. it must chill 5MW of heat from an area about the size of a 25 cent coin. i calculated that ~2kg/s of helium would have to pass over this area to meet the specification, with the nozzle pressurized to 175 atmospheres. since the secondary coolant is water, the gas entry temperature will be ~373 kelvin (water's boiling point).

assuming choked flow, the gas reaches about the speed of sound in the nozzle. what is the speed of sound in helium under these conditions?

mirror matter has recently been proposed to explain galactic rotation anomaly. but why would/should the mirror matter be distributed at the galactic halo in absence of ordinary matter? why would it not be distributed uniformly?

http://www.physorg.com/news191562687.html

I'm not quite getting Paschen's law, yet.

a pair of pipes, arranged coaxially, is filled with Ar+SF6 mixture at 1atm,

and charged to 60 kV. what is the minimum gap to avoid arcing?

http://home.earthlink.net/~jimlux/hv/paschen.htm

A copper pipe of length 10m is found to carry 106,250 A at 30 kV DC, with rise time = 1.8 μs.

what is the diameter of the pipe?

"Unlike the galactic disc, the halo seems to be free of dust, and in further contrast, stars in the galactic halo are of Population II, much older and with much lower metallicity than their Population I cousins in the galactic disc (but similar to those in the galactic bulge). The galactic halo also contains many globular clusters." -- http://en.wikipedia.org/wiki/Spiral_galaxy#Galacti...

this begs the question,

How do you know that Population II stars are much older?

c = 1/sqrt(ε₀*μ₀), and is assumed to be a universal constant, but i see no good reason why ε₀ and μ₀ are necessarily isotropic.

if such an anisotropy affected c in something like the fourth or fifth digit of precision, how would it be detected?

it is said that the Fay-Riddell expression is

"a relatively compact closed form equation used to model the convective and catalytic heat flux at the stagnation point of an aeroshell."

But what is the formula? What do its parameters represent? and when is it applicable?

while answering another question, someone said that "the L/R ratio will be the time constant which will determine the rise time." I know that L stands for inductance, and R for resistance, but

How is the rise time calculated? what is this formula that includes the L/R ratio? thx

A suitably large capacitor bank with negligible inductance, is charged to 50kV, then discharged through a hollow, copper pipe, 13.5cm diameter, 10m long, and 25 µm thick. What is the peak current? What is the current rise-time?

http://www.myelectricengine.com/projects/mpdthrust...

some time ago, my brother made a batch of sourdough, but it spoiled.

i'm looking for tips on how to do this better?

i set out some whole wheat-flour in water. after 3 days there is no sign, yet. should i stir this? try different mixtures and proportions?

room T=28°C, humidity moderate, for winter (outdoors is ~4°C and very humid.)

A small rocket is launched from a canon at Earth's equator at sea level, P=1 atm. T=25°C.

This rocket consists of a cylinder, length =1.2m, diameter =0.4m,

plus a parabolic nose cone, retractable fins, engine, fuel, and payload;

total mass =450 kg.

At exit from the canon barrel, if the speed is 6.0 km/s,

1. calculate the force of atmospheric drag, in Newtons

http://en.wikipedia.org/wiki/Drag_(physics)#Drag_a...

2. calculate the heating in W/m² on the nose

3. what would these values be if the nose is dimpled at the surface, like a golf ball?

Orange dwarf star HD 156668 is listed as spectral class "K2V". Apparent magnitude=8.42 and distance=78.5 ± 2.0 ly. I'd like to know its mass, luminosity, temperature, and age.

Wikipedia tells me K-type stars are 3500..5250 K, and 0.08 .. 0.6 L(sol). but that's a big range; can you help me get this down to a more precise value? thx

for service from Earth's equator to geostationary orbit?

http://en.wikipedia.org/wiki/Specific_strength

on Mars, a glass dome, 1 km^3 volume, is built from local materials and contents pressurized to between 30 and 50 kPa.

if the glass has an ultimate strength of 3MPa, how thick do the walls have to be to maintain the pressure?

imagine you have a 300km length spool of high tension cable, with ultimate strength = yield strength = 3 gigapascals, and a cross-sectional area of 10 cm^2. you bring this to low-earth orbit ~250 km elevation, and begin to cast it out behind you.

1. as the cable spools out, it begins to align itself radially, due to tidal effects. is the tendency for the end to hang toward the nadir or zenith?

2. if the density of the cable is 5 g/cm^3, can you cast out the whole spool without it breaking? if not, how much will cast out before it breaks?