113,972 reputation
5176303
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 10 months
seen 8 hours 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.


9h
comment How to determine speed/energy of something dropped from a given height?
This article on Hyperphysics goes through all the details. Be warned that the maths can get a bit hairy for beginners. Googling something like trajectory drag will find you lots more articles on the subject.
10h
comment Does the work function of metal depend upon the intensity of light?
@honeste_vivere: a dilute metal gas won't conduct electricity and will not have a work function. The atoms will have an ionisation energy, but the ionisation energy of atoms is typically around 5eV or a factor of 2 - 3 times greater than the work function of metals.
10h
comment How does air in a water balloon act in space?
It behaves like this
16h
comment How are the half life of particles mathematically related to the inverse square laws?
The inverse square law only applies when the paricles don't decay i.e. their half life is infinite.
17h
comment Black holes and positive/negative-energy particles
Re Danu's comment: the draft appears to be titled Introduction to Quantum Fields in Classical Backgrounds, but a quick comparison with the Google Books copy of Quantum effects in gravity suggests they are the same book. Thanks Danu, another addition to the large pile of books to be read one day.
19h
comment How does virtual particle become real particle in Hawking radiation?
The virtual particle explanation is only an analogy and not to be taken seriously. See the linked question for what actually causes Hawking radiation.
1d
comment How did the Huygens probe use EM waves to measure wind speeds on Titan?
@karthikeyan: the experiment measured the lateral speed of the Huygens probe. Because the probe is dangling from a parachute being swept along by the wind it's assumed that the lateral speed of the Huygen's probe is roughtly the same as the wind speed. So this gives us an indirect measurement of wind speed.
1d
comment Show that there exists a Lorentz transformation such that two events are happening at the same time?
Consider what happens to the $x'$ axis as you increase the boost.
1d
comment Why are dishwasher washed glasses “squeaky clean”?
@PiotrDobrogost: sodium hydroxide reacts with silica to produce sodium silicate, so sodium hydroxide will dissolve silica but only exceedingly slowly. However this is chemistry not physics.
1d
comment Is uncertainty in velocity via HUP reference frame dependent?
Agreed. First year students tend to be taught an over-simplified and potentially misleading version of the uncertainty principle, presumably to stop their brains melting. If it's OK I'll flag this as a duplicate of the question I linked above.
1d
comment Is uncertainty in velocity via HUP reference frame dependent?
Yes, I am saying the uncertainty does not arise from your measurement technique. See Is uncertainty principle a technical difficulty in measurement? for more on this.
1d
comment Is uncertainty in velocity via HUP reference frame dependent?
If I measure a velocity as $v \pm \Delta v$, then the uncertainty is $\Delta v$ and whether $v$ is large or zero makes no difference. From purely practical considerations it's probably easier to measure a velocity accurately if it's small, but the error due to the uncertainty principle is not due to practical considerations.
1d
comment Has the formation of a new quark pair as we separate two quarks been observed or is it only a prediction?
It looks as if the OP is happy with the answer in my comment, but I have to say the proposed duplicate doesn't look like a useful duplicate to me i.e. an answer to the duplicate is unlikely to answer this question.
1d
comment Is uncertainty in velocity via HUP reference frame dependent?
Why would the two observers measure a different uncertainty in the velocity?
1d
comment Will the usage of Exo-Skeleton Gear actually weaken the human body over time?
My thoughts are that this isn't a question about physics.
1d
comment Net work done for rubber bands
@user143525: Energy has do go somewhere. If you put some amount of work in, and get a lesser amount of work out, then the difference must go somewhere. In this case it goes into molecular excitations of the rubber polymer molecules - in other words heat. NB I'm assuming the strtetching and relaxing is done slowly so any kinetic energy can be ignored.
1d
comment Has the formation of a new quark pair as we separate two quarks been observed or is it only a prediction?
It's the mechanism for jet formation. To that extent it is observed at every collision in the LHC.
1d
comment What happens to an orbiting body moving with the Earth's angular speed at various altitudes?
@JoshuaLin: oops, yes. Thanks :-)
2d
comment Why do my hairs get stuck to my cathode-ray TV screen after it is switched off?
Note that the hairs don't need to be charged to stick to the screen. The electric field near the screen will polarise the hairs and the resulting electric dipole is attracted to the screen. This effect is why a comb can pick up uncharged pieces of paper in the notorious school experiment.
2d
comment What happens to an orbiting body moving with the Earth's angular speed at various altitudes?
Aha. That will be down to me not using a sidereal day.