Reputation
442
Top tag
Next privilege 500 Rep.
Access review queues
Badges
2 8
Newest
 Yearling
Impact
~12k people reached

  • 0 posts edited
  • 1 helpful flag
  • 60 votes cast
1d
comment If we threw a baseball from the ISS, could we deorbit the ball?
@pentane As important as it is to replace the pump. In the longer term it is also very important to postmortem why the pump failed, for when they can't replace the pump (on Mars).
May
3
comment How is 6W equivalent to 40W, as claimed by adverts for LED light bulbs?
@SeñorO How does one get an efficient space heater? Mine is only 100% eta (Q/W)!
Apr
17
comment Can 2 photons make up the same colour as another photon?
I think the OP is asking if two photons can combine together and produce a third photon with their combined energy. You should look into non-linear optics. It's the basis of how the green laser pointer works.
Mar
29
comment About speed of sound?
In short, for the purposes of your question, sound ALWAYS travels 342m/s. The question is whether (it is loud enough for) you (to) hear it or not at the other end.
Mar
28
comment How can a gas giant be about the same size but six times more massive than Jupiter?
@Joshua but how would such an object form without heating up? I mean all that mass must have kinetic energy equivalent to the binding energy of the body to begin with...
Mar
24
comment Why does moonlight have a lower color temperature?
@RobJeffries My point being is that the energy spectra has been thermalized a process that takes a long time in the sun, which gives characteristics of a Blackbody emitter. The light (reflected) from the moon does not go through a process that thermalizes it. What you said is like saying that 'neither a flame nor a mirror has a "colour temperature" because neither are true black bodies'.
Mar
24
comment Why does moonlight have a lower color temperature?
@RobJeffries That is one interpretation, certainly. However the photosphere gets its energy from photons from the core. We can model the process as a photon making its way out from the core scattering constantly. Then we can model that process as Brownian motion. Of course its all approximate. But by your reckoning there is no such thing as a Blackbody.
Mar
24
comment Why does moonlight have a lower color temperature?
@RobJeffries I disagree with you. The sun might generate energy through fusion, which produces a defined (photon) energy spectrum (non-thermal). But those photons are created in the core. It takes many (thousands of) years for the photon to make it to the photosphere, where we finally can observe it, by which time it will have thermalized.
Mar
14
comment How to cut a stone on a White Dwarf?
@MitchellPorter " Once a white dwarf cools down", its not a "white" dwarf.
Mar
4
comment Is it possible for a crystal to have different structures at different temperatures?
Perhaps the most dramatic example of this is in the two "common" allotropes of Carbon.
Mar
3
comment Beyond the speed of light
STEP 2 does not exist. There are no finite number of steps to reach your "step 2". Your question is meaningless.
Feb
29
comment Liquid conductors and conservation
Not to mention that "conductive" ions are by definition, "not in the ground state". This gives rise to a lot more scattering pathways (resistance).
Feb
19
comment Long and short barreled guns
@user1717828 As dmckee said. The basic assumption is that the gun maker wants to make his guns all just as powerful. So to offset the smaller barrel, he uses a larger charge.
Feb
19
comment Long and short barreled guns
@user1717828 The hot gas in the barrels do the same amount of work. The difference the barrel. Within the barrel, the hot gas can only do work on the bullet. Once the bullet leaves the barrel, the hot gas does work on both the bullet AND the atmosphere. The shorter barrel allows the gas to do MORE work on the atmosphere, thus, LESS work is done on the bullet.
Feb
19
comment Long and short barreled guns
@user1717828 The longer barrel doesn't subject it to less acceleration. The longer barrel subjects the bullet to longer acceleration. The physics involved is called "Internal Ballistics", but the important part is that a bullet accelerates because there is pressure behind it. There is pressure behind the bullet because there was an explosion AND the barrel prevents the gases from expanding. When the bullet leaves the barrel, it stops accelerating. The reason for the lower acceleration comes from the assumption of a constant muzzle velocity, ie the long barrel ALLOWS for lower acceleration.
Feb
19
comment Long and short barreled guns
Take down your comment, it has nothing to do with friction. Its simply due to the equation E = Fdx. Given a longer barrel (dx), the required Force (F) is smaller for the same Muzzle Energy (E).
Feb
19
comment Long and short barreled guns
A really good answer to this question was posted by Scott Manley on Youtube, but with a slightly different premise. Why can't we fire humans into space?
Feb
18
answered Short of collision, can gravity itself kill you?
Feb
18
comment How does the curvature of spacetime exert a force on a stationary object?
It does not exert a force. The curvature of spacetime redefines an inertial frame such that it is accelerating wrt a Newtonian inertial frame.
Feb
17
comment Spin $1$ vs. spin $1/2$
The main consequence of spin 1 is that it makes the particles Bosons (ie excluded from the Pauli Exclusion Principle) and the other is that the magnetic field can orient itself in three directions: parallel, perpendicular, and antiparallel to the field.