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location Netherlands
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visits member for 3 years, 11 months
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21h
comment Is this particle reaction possible?
That's a good reason why it's not allowed. Of course, there could be multiple reasons, and it's not like nature checks them in a specific order.
Oct
15
answered Planets and Pluto? Neptune?
Oct
15
answered Can Thermal Energy be converted into usable energy?
Oct
12
comment Benefits of rear spoiler in cars
The problem with this theory is that you need to exert an upward force on the air over the spoiler to get downforce, but to decrease that low-pressure zone you'd have to send air downwards. A spoiler beneath the car seems to make more sense.
Oct
12
comment Is it possible to start fire using moonlight?
Your argument about black-body radiation from the moon holds for a new moon. I'll bet that agrees with your gut feeling. With a full moon, you're discussing reflected sunlight which isn't in thermal equilibrium with the moon surface.
Oct
1
comment Why do rockets jettison fuel tanks?
Actually, as most Kerbal Space Program players know, you don't need extra engines even if you have stages. You just have to attach the tanks to the side instead of stacking them. In reality, there's another benefit: if you have multiple engines, you can optimize them for different ambient pressures and trust levels.
Sep
26
comment Machine to identify substances
That "White laser" might be hard to source.
Sep
22
answered Forces on objects orbiting a black hole?
Sep
22
comment Forces on objects orbiting a black hole?
More than one, in fact.
Sep
16
comment A basic math identity often used in integrals
"Linear Algebra is linear". In the end, it's that simple. The multiplication is just a basis transform. Physical reality does not change by your arbitrary choice of a basis, so the (differential) equations describing reality should hold up in any basis.
Sep
16
answered Forces while squeezing a toothpaste tube
Sep
16
answered Pulling apart two interleaved phone books
Sep
16
comment What makes a material adhesive (or sticky)?
Just to check: there's adhesive on the tape? IOW, one side is much more sticky than the other? If you'd make a moebius strip the wrong way around, it wouldn't bond? Those are easier to design, as the designer has freedom to choose both adhesive and substrate.
Sep
9
comment Is a plasma necessarily made of monoatomic ions?
Good question. The electrons that form the molecular bonds are those which are most weakly bound in the first place. That's why they're orbiting between two atoms, instead of orbiting just a single atom. And those weakly bound electrons would probably be the first to affected in ionization. Either they're stripped off, or they pair up with a donated electron instead. Either way, they no longer pair up to form a molecular bond. This simple theory does predict that molecules with a double bond are more likely to survive ionization. An O2- ionized molecule still has one bond left.
Sep
8
awarded  Nice Answer
Sep
1
answered How quickly should a fluid come to hydrostatic equilibrium?
Sep
1
comment How quickly should a fluid come to hydrostatic equilibrium?
@Graviton: The "absence of gravity" which you describe is initially a lack of support on the bottom of the bottle - we may assume this is instant. However, this means the bottommost water molecule is accelerated down because of the pressure of the water above it. This creates an initial pressure wave travelling up, and that's indeed at the speed of sound described by Mark. That wave will indeed hit the cap after ~20 ms, reflect, etc. The top water molecule can't notice that the bottom has dropped until the pressure wave hits.
Aug
28
comment Is the Big Bang defined as before or after Inflation?
TBH it's entirely reasonable to use the term in astrophysical contexts such as "One billion years after the Big Bang ...". The term is only troublesome if you need to distinguish the phases of the early universe.
Aug
15
comment Does large acceleration have to cause damage to the human body?
@Trimok: I'm fairly certain that the parachute jumper is accelerating with 1g when he leaves the plane, unli air resistance catches up (at which point it's no longer a free fall, strictly speaking)
Aug
15
comment Does large acceleration have to cause damage to the human body?
@MariusMatutiae: You can't really switch on and off gravity, but let's assume for a moment that you can: when turned on, it would accelerate your internal organs at the same speed as your bones.