104,567 reputation
4152276
bio website ratsauce.co.uk
location Chester, United Kingdom
age 53
visits member for 3 years, 8 months
seen 2 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.


Apr
3
comment Kinematics, why must the final velocity be 50km/hr?
To be fair it would be a great deal of work to put all the details in the question as it would require reproducing large parts of the paper.
Apr
2
comment Is the Hilbert-Felber model of repulsive gravity correct?
Aaah... I wonder if, in the rest frame of the distant observer, the object never passes the black hole but gets continually pushed along in front of it and therefore accelerated to the same speed. If so I'm not sure how you'd get off the train.
Apr
2
comment Is the Hilbert-Felber model of repulsive gravity correct?
@AndrewPalfreyman: yes, but after the black hole has passed, why isn't the effect reversed leaving the object displaced but stationary?
Apr
2
comment Centrifugal force when there is no friction
possible duplicate of Direction of friction on particle placed on a rotating turntable
Apr
2
comment Light and Prisms
However, your LCD screen and/or phone produce pretty convincing pictures using just RGB, so RGB reproduces enough colours to convince.
Apr
2
comment Light and Prisms
@jinawee: If the cone cells just responded to pure red, green and blue light then RGB would be able to produce every colour the eye could see. However the cone cells respond to a broad range of wavelengths (as shown in the graph in my answer) and their ranges overlap. That means there will be some combinations of cone cell response that cannot be expressed as a sum of the individual responses to just red, just green and just blue light, and hence there are some colours that can't be reproduced using RGB.
Apr
2
comment Centrifugal force when there is no friction
If there is no friction the coin will remain motionless where it is while the disk rotates underneath it.
Apr
2
comment Light and Prisms
The other one is probably CMY (or CMYK). RGB is additive mixing, like the screen on your phone, and CMY is subtractive, like your inkjet printer.
Apr
2
comment Light and Prisms
Do you mean what colour do you get if you mix yellow and green light? If so yellow is (as far as our cone cells are concerned) a mixture of red and green light, so mixing yellow and green would be seen as yellowy-green.
Apr
2
comment How long does it take for an electric car to go from 0 to 60 mph?
The freefall equation is complicated because the force changes with distance from the planet. For a car accelerating at constant acceleration just use $v = u + at$.
Apr
2
comment How fast does it take to create a magnetic field in a solenoid?
$B \propto Vt/L$, so if $V = 10$ and $L = 1$, $B \propto 10t$ and the field increases at ten times the rate time does. The time constant really comes from the solution to the equation when resistance is present, in which case $B$ tends to its maximum value exponentially.
Apr
2
comment Non-uniform lens flares
possible duplicate of How to correct flares and sharply focus on my telescope when viewing planets.
Apr
2
comment How fast does it take to create a magnetic field in a solenoid?
Cool :-) Though it's possible the magnet's control circuit is slowly ramping up the power. It may not just be the inductance of the coil.
Apr
2
comment Colliding particles at speeds aproaching c
You just need the total energy measured in the lab frame to equal 5.6GeV. With this energy the two particles could fuse to create a stationary particle of mass 5.6GeV.
Apr
2
comment Is this oscillator driven?
I don't think any damping is implied. This is a regular SHO and you just need to calculate the force constant $k$ so you can calculate the frequency. You get the force constant from how much the spring extends before the mass is brought to a stop.
Apr
1
comment Potential energy of an infinitesimal length of elastic rod
The potential energy is equal to the work done. Since energy is conserved, if you do work on the system that energy must go into potential energy. So $dU$ and $dW$ are effectively the same.
Apr
1
comment PN Junction. Germanium VS Silicon
Are you asking about a Si-Ge junction, or about the junction between P doped and N doped silicon compared to the junction between P doped and N doped germanium?
Apr
1
comment Origins of many-particle interactions
@DumpsterDoofus: but if you look at your monopole-dipole system at the level of individual electrons and protons the potential is a simple pairwise sum. It only appears otherwise because at the larger scale you are ignoring the motions of the individual charges.
Apr
1
comment When one monkey accelerates up a rope, what happens to the other?
See also: Movement of man and ladder and their center of mass
Apr
1
comment How does a simple weighing balance actually work?
In real life balances are always designed so the centre of mass is below the pivot. This is discussed in a couple of the answers to the previous question about balances.