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 Yearling
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Jan
24
revised XP Decay mode of radioactive nucleus
fixed typos
Dec
19
awarded  Yearling
Dec
14
comment What would happen if the Earth was in a polar orbit around the sun?
Would rotating the Earths orbital plane affect perturbations from the rest of the planets to a significant amount?
Nov
19
comment Could we launch a missile from a planet with the mass of Jupiter?
@WetSavannaAnimalakaRodVance Hal Clements Mesklin (Mission of Gravity, Whirligig World, Heavy Planet) with conditions of several hundred g's at the poles would be a better SFnal reference.
Sep
18
comment How far out from the Sun is visible light still sufficient to read a book?
@Jitter Excluding a few comets, the dwarf planet Eris is the most distance known object in the solar system at 96 AU.
Sep
16
comment When I boil a kettle, what stops all the water from turning (exploding!) in to steam in one go once it reaches 100°C?
If the sort of accident you're describing in the last paragraph does largely empty the cup/etc; it's because bubbles formed so rapidly that they expelled a majority of the water the container in liquid form.
Mar
23
comment What if you opened a door in a spaceship without a spacesuit?
It's worth noting that the calculation in that answer for the force of outrushing air used a 20m^3 volume. That's much larger than a plausible personnel airlock would be.
Jan
18
comment How bright is a 150 W incandescent light bulb?
150W equivalent bulbs on amazon.co.uk. In the US higher wattage CFLs are also generally available in larger home improvement stores.
Jan
18
comment How bright is a 150 W incandescent light bulb?
@ColonelPanic you need to shop around more. Amazon has CFLs in the 2600-2800 lumen range; most of them run ~40W though. The potential gotcha is that they're noticeably larger than a standard incandescent bulb; and may not fit in fixtures that were designed to be barely big enough for a standard size incandescent. I believe the size constraint was why the US ban on incandescent bulbs stopped at the 100W size.
Jan
8
comment Why are grams usually only expressed as milligrams, grams or kilograms?
A dozen years ago my undergrad astrophysics classes all used cgs units as well.
Dec
19
revised Does gravity travel at the speed of light?
Updated date; schedule appears to've slipped slightly since my original post.
Dec
19
awarded  Yearling
Oct
25
awarded  Nice Answer
Oct
24
answered 6 wheels more efficient than 4 wheels?
Aug
13
comment Put a bullet into orbit around the moon
@Cruncher There don't appear to be any commercial rifle rounds that fast. The fastest Wikipedia lists is the .223 WSSM @ 4520 feet/sec ~ 1380m/sec. The 120mm cannon used on the M1 Abrams can reach 1750m/sec. This suggests that a rifle capable or reaching that muzzle velocity should be possible in theory; however keeping the recoil to something the human body can handle could be problematic. Assuming it wouldn't result in a kaboom I'm sure there're hand loaders who'd be willing to try if you provided them transport.
Jul
30
comment How did they take photos of Jupiter?
I'd add that most amateur images of the planets are made using a video camera and the combining the handful of best frames (from when the air was exceptionally steady) from several minutes of recording (longer than that and motion blur becomes a problem due to rotation).
Jul
30
comment How did they take photos of Jupiter?
@kasperd The separation between Jupiter's moons and the shadows they cast on the planet can be much larger than in the OPs picture. ex in this amateur picture the shadows are on the left edge of the planet while the moons are to the its right. Both moons are in the segment of their orbits that is mostly between earth and Jupiter but slightly to the right. (IO orbits at ~ 5 R_j; the other major moons are several times farther out.)
Jul
21
comment Neutrino annihilation and bosons
Were you thinking of neutrino absorption? I've seen estimates that layer of matter just outside the core in a supernova collapse is dense enough to absorb ~10% of the neutrino flux produced within the core itself; but don't recall seeing anything about neutrino annihilation before.
Jun
6
comment Why does a ball bounce lower?
Is the sound made when the ball bounces also carrying away frictional energy from the deformation?
May
23
comment How intense a magnetic field would it take to keep an hypothetical iron-made moon orbiting around it?
@Joshua I think you're remembering that there're no stable orbits with 4+ spacial dimensions; off hand I'm not sure if that would be a problem for a magnetic orbit or not. askamathematician.com/2012/05/… (~3-4 screens down)