136,127 reputation
9228378
bio website ratsauce.co.uk
location Chester, United Kingdom
age 54
visits member for 4 years, 4 months
seen 1 hour 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.


2d
reviewed No Action Needed Confusion about two forms of connection coefficients
2d
reviewed No Action Needed $F=ma$, so if acceleration is zero the force must also be zero?
2d
revised “Shortest” path in general relativity
Minor tweak
2d
comment “Shortest” path in general relativity
@Alexander: oops, thanks :-) Please free to edit obvious typos.
2d
revised “Shortest” path in general relativity
Typo
2d
answered “Shortest” path in general relativity
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reviewed No Action Needed can we see or accumulate antiparticles
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reviewed No Action Needed Balloon aerodynamics
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reviewed No Action Needed Twin paradox, with a meeting at a halfway point
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reviewed No Action Needed $F=ma$, so if acceleration is zero the force must also be zero?
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reviewed Leave Open Which electrons in copper are involved in electric current flow?
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reviewed Leave Open Why doesn't Beta Decay violate the laws of physics?
2d
reviewed Close What is the ratio of Poisson's number for air?
2d
reviewed Close Graphene plasmonics, Integro-differential eigenvalue equation
2d
reviewed Close Easy to use particle tracking software
2d
reviewed Leave Open Has the effect of magnetic fields on time ever been examined experimentally?
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reviewed Close How to calculate meters per second speed when i have distance in meters and time in minutes
2d
reviewed Leave Open Net force between two Electromagnets considering Back EMF
2d
comment Find distance vs. time for a space ship moving through cloud of dust of uniform density
You haven't been solving differential equations for forty years like me. One gets lazy in ones old age :-)
2d
comment Find distance vs. time for a space ship moving through cloud of dust of uniform density
The mass at distance $x$ is $M(x) = m+A\rho x$. Conservation of momentum means $mv_0 = M(x)v$ so we get the equation $v = \frac{dx}{dt} = \frac{mv_0}{m + A\rho x}$. This is a straightforward integration and gives $\tfrac{1}{2}A\rho x^2 + mx = mv_0t$. Solve the quadratic to get $x(t)$.