135,918 reputation
9228377
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 4 months
seen 44 secs ago

Semi retired old time computer nerd who started programming on a Commodore Pet.

Since I'm also active in the Physics forum I should add that I started as a theoretical chemist, moved into solid state photochemistry and finally worked in industry as a colloid scientist. I only became a full time computer nerd in 1997.


1d
comment What does this problem about lenses really want?
Objects at infinity form an image at the focal length, so I interpret the question to mean that the focal length of the lens is 40mm.
1d
comment What does this problem about lenses really want?
Hi and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
1d
comment Where does the majority of the mass of the usual matter come from?
possible duplicate of From which dimensionful constants does proton mass arise?
1d
comment neutron stars and black holes lifespan
I answered your question (2) here.
1d
comment It's All About Earthquake!
The Richter scale measures the amplitude of seismic waves, which is related to the energy released. A change in magnitude of one means the amplitude of the seismic waves changes by a factor of ten and the energy changes by a factor of about 32. There are full details on this site if you're interested in following this up.
1d
comment Why does a circle of light form around a wire when a laser is pointed at it?
Hi Macro. As it stands, your question is a duplicate. If you have a calculation showing that the pattern observed can't be due to reflection you could explain the calculation in your question.
1d
comment Why does a circle of light form around a wire when a laser is pointed at it?
possible duplicate of Laser, wire, and a circle of light
1d
comment How does newtons third law help explain interaction between charged objects?
Hi Hilary. Newton's 3rd law is basically a statement that in any interaction momentum is conserved. It's not obvious to me that it has anything specific to say about charged objects, as opposed to any other kind of object. Can you give us a bit more context? Can you post a link to the article or maybe edit your question to include a quote from it?
1d
comment Distance travelled by boat!
Hi Jack and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
2d
comment Relativity question about 4-velocity
@user145974: I think Kyle's point is that this seems an awfully large hole in your knowledge of differential geometry, and you should fill it asap. Having said that, the co and contravariant distinction and the whole business of raising and lower indices confused the hell out of me at first :-)
2d
comment Moving Around Space Without Propellant
See my answer to Intuition as to why the orientation (of a 3D object) is not a conserved quantity? for a proof that the position of the centre of mass of an isolated system cannot change.
2d
comment Luminous flux density by using Lambert's cosine formula
Hi Harish and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
2d
comment what size puddle does a gallon of water produce?
@jameslarge: in that case the contact angle will be approximately $\pi$ so $\cos\theta \approx -1$. You just need to Google for the surface tension and density of coffee (the density will be very close to the density of water).
2d
comment String wrapping around a motionless cylinder
Hi and welcome to the Physics SE! Please note that this is not a homework help site. Please see this Meta post on asking homework questions and this Meta post for "check my work" problems.
2d
comment A Relativity question about radial acceleration?
Hi Sophie. The question I've linked is calculating the weight, but it calculates the norm of the 4-acceleration as an intermediate step.
2d
comment Free-falling from rest into a Kerr black hole
@PeterShor: forgot to divide by 2? :-)
2d
comment Does the Holographic Principle explain Dark Energy?
I'm voting to close this question as off-topic because it is founded upon a misapprehension
2d
comment Compare phase spectrum and magnitude spectrum
That's an awfully broad question. Can you be a bit more precise about what you want to know?
2d
comment Stern-Gerlach experiment need for collimated beam?
Any angular spread in your beam will blur out the spots and maybe even make them merge so they can't be seen.
2d
comment Electric Flux through cube
I'd be inclined to consider the flux through the eight cubes surrounding your point charge then divide by eight.