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Started programming on a ZX spectrum in the 80's and have moved through Assembly, Turbo Pascal, C++, C#, Fortran. My main area of focus is engineering and scientific computing like numerical methods and 3D graphics.


11h
comment Why do ships lean to the outside, but boats lean to the inside of a turn?
So the quick answer here is because they are designed to do exactly this. Btw, cool pictures.
11h
comment Calculating force of a car
possible duplicate of How to get distance when acceleration is not constant?
12h
comment Calculating force of a car
You need to explain what is wrong with the results.
13h
revised Moment of inertia of a cylinder about its base
added 18 characters in body
13h
comment Moment of inertia of a cylinder about its base
To define the inertia tensor you need $$I= \int \begin{pmatrix} y^2+z^2 & - x y & - x z \\ - x y & x^2+z^2 & -y z \\ -x z & -y z & x^2+y^2 \end{pmatrix} \,{\rm dm}$$ most of the terms fall out for a symmetric shape. This is a result of the vector form of the parallel axis theorem ${\rm d}I = -{\rm d}m [\vec{r}\times][\vec{r}\times]$.
13h
revised Geometry in diagonal matrix and inertia tensor
Fixed typo in element [2,2] of mass moment of inertia tensor
13h
comment Moment of inertia of a cylinder about its base
Related: physics.stackexchange.com/a/111081/392
13h
comment Moment of inertia of a cylinder about its base
@Fadi the parallel axis theorem has to do with calculated mass moment of inertia about an axis away from the center of mass. Here the end axis is $\frac{L}{2}$ away from the COM. I mentioned this because of the definition of the mass moment tensor arises from the parallel axis theorem. See physics.stackexchange.com/a/111081/392
1d
comment How to determine direction of forces in a static problem?
The convention is positive for tension, and negative for compression.
1d
revised Moment of inertia of a cylinder about its base
added 248 characters in body
1d
answered Moment of inertia of a cylinder about its base
1d
comment Moment of inertia of a cylinder about its base
Check the factor in front of the double integral. It should be equal to $\rho = \frac{M}{\pi R^2 H}$ since $I=\int \rho d^2 \,{\rm d}v$ where $d$ is the perpendicular distance from the axis of rotation.
1d
answered Why do we take small steps while walking on ice?
1d
answered Deriving spring oscilation period
1d
revised Deriving spring oscilation period
added 1 character in body
1d
comment Deriving spring oscilation period
Aghh, you should use math formatting for better readability.
Jul
28
comment Lifting frictional force and relative values for kinetic vs static friction
Related paper: ewp.rpi.edu/hartford/~ernesto/F2012/FWM/Papers/Childs-App3.pdf
Jul
28
comment Doubt in collision
Note $F=m g$ ONLY applies to a static case. Here as the ball experiences acceleration it is dynamic with $F-m g = m a$
Jul
28
comment Work done by a frictional force on a cylinder
I meant is there anything else pushing the cylinder besides friction?
Jul
28
answered Work done by a frictional force on a cylinder