640 reputation
716
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location London, United Kingdom
age 30
visits member for 3 years, 11 months
seen Sep 4 at 18:03

Phd student


Jun
30
comment On a bicycle, why does my back tyre wear so much more quickly than the front?
Sorry but there are a couple of incorrect assertions and even more spelling mistakes in this, hence a -1 I'm afraid.
Jun
29
comment Collision between a rod and a bullet
@Willie: I see what your saying, I hadn't thought of it that way but now you mention it I agree that two collisions could be possible.
Jun
29
comment Collision between a rod and a bullet
Interesting question. My 'hunch' would be that if the rod is indeed considered "rigid" (which is obviously not physical) the maximum number of collisions would be one. That said, I'm not sure I personally am capable of showing this using conservation of linear and angular momentum. I'll try a little back-of-an-envelope calculation later this afternoon..
Jun
28
comment What if the LHC doesn't see SUSY?
Very interesting reading @Lawrence (+1.) @anna I just wondered if you had an opinion on 'proton-driven plasma wakefield accelerators'? See pg 18 on the slides of this recent talk for example: c-ad.bnl.gov/pac2011/proceedings/talks/tuobn5_talk.pdf Could this scheme ever be implemented in the main LHC tunnel in the years to come, and what energy lepton beams might this offer?
Jun
24
comment Why is the decay of neutral kaons (violates CP invariance) seemingly not sufficient enough for certain people to describe matter-antimatter imbalance?
+1 for "..this is a family site." Haha
Jun
24
comment Does particle indistinguishability and quantised enery levels (in bound states) violate the Pauli Exclusion Principle?
@Gigacyan: Sure is, duly accepted. Cheers
Jun
22
comment electron orbits
Hyperphysics has a nice exposition on this: hyperphysics.phy-astr.gsu.edu/hbase/hyde.html
Jun
22
comment electron orbits
@dmckee: I did say it was a simplistic answer ;-)
Jun
22
comment Ascent rate and size of balloon
@Cameron: You could calculate a rough estimate by doing a little experiment - Get one of the balloons you intend to use and inflate it until it pops. If you know the pressure difference between inside and out when it pops, you could predict at what height this same pressure difference would occur. Since measuring the pressure in the balloon may be difficult in practise, you could calculate it if you measured the size and (negative) weight of the balloon, up until the moment it bursts.
Jun
22
comment electron orbits
A simplistic answer: if a single electron, bound to a proton, absorbs a photon, the electron will be excited into a higher energy state. If the photon absorbed is higher than the ionization energy, the electron will be liberated from the atom. Therefore the highest energy state the electron could occupy, without being ionised, would be the state closest to the ionization energy (from below.)
Jun
22
comment Function of electric water pump
That just depends on which way around you connect the two pipes to it.
Jun
21
comment Energy produced by a swing?
Hi @Seb, the GPE and KE are the two forms the energy could be in. The total energy available in the system is $E=GPE+KE$. When the swing is high it is changing direction, which implies the velocity is zero and therefore the KE is zero. All the total energy is therefore all in the form of the GPE at this moment. When the swing is low, the velocity is maximum, and therefore so is the KE. The GPE is necessarily zero at this point. All of E, GPE and KE are energies - so yes, they are all measured in Joules.
Jun
19
comment a question on Lagrange's equation when the time derivative of the generalized co-ordinates is constant
I see what you're getting at but this is too brief to be an answer. Perhaps you could change it to being a comment or edit your answer to elaborate. -1 until then I'm afraid.
Jun
18
comment Formulas for ball rolling in a bowl?
@Dane: See also this question physics.stackexchange.com/questions/11227/…
Jun
18
comment Analyzing the motion of a ball rolling without slipping inside a hemispherical bowl
Closely related: physics.stackexchange.com/questions/10798/…
Jun
16
comment Does particle indistinguishability and quantised enery levels (in bound states) violate the Pauli Exclusion Principle?
@gigacyan: Having just finished another read-through of this page I wondered whether you would edit your answer to include the essence of our discussion in its comments. After which, I would be happy to accept it :)
Jun
16
comment heliocentricity and the theory of relativity
I would go as far as to say this is a duplicate of the question in @Qmechanic's comment. @statichippo: regarding your last paragraph - indeed, no need to worry about that here :)
Jun
15
comment What happens when two D-branes annihilate?
@Hiatus: To my mind, your comment seems sufficient for an answer.
Jun
15
comment Stronger than Newton's laws?
@Marek: Here, here! I'd vouch for those to comments to be posted as an answer (minus the 1st sentance perhaps ;) Upon seeing it, I will certainly cast a +1 vote on it.
Jun
15
comment Stronger than Newton's laws?
Continued.. I suspect, however, that in practice this would be of very limited use - Newton's Laws work fine as they are and their power, in some respect, comes from their simplicity and ease of use. Given that QFT is already complex enough to solve for elementary particle interactions, it would likely be extremely difficult to show that it can be reduced to Newton's 2nd Law for the many-particle systems, that comprise the macroscopic bodies, to which Newton had intended it to apply. In summary, I don't feel this question is worth losing much sleep over, even if it is solvable analytically