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visits member for 4 years, 9 months
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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. #SOreadytohelp


Aug
7
comment Force needed to deflect a gyro
You know that $$\frac{{\rm d}\vec{L}}{{\rm d}t} = I \dot{\vec{\omega}} + \vec{\omega} \times I \vec{\omega}$$ since the mass moment of inertia changes with orientation.
Aug
7
comment Can photons accelerate?
Photons slow down when entering dense media. So they must accelerate afterwards when they leave.
Aug
5
answered How do I know what variable to use for the chain rule?
Aug
5
comment Why aren't all points on a rolling ball moving?
Any body moving in a plane will have one point with no instantaneous velocity. This point might be on the body, or away from the body. At that instant all distances from the points on the body to this point remain constant. The body spins about this point.
Aug
4
comment What happens when two photons collide with one another, head on, dead center?
Where is the center? Heisenbeg would prevent you from specifying dead center aiming.
Aug
4
answered Why aren't all points on a rolling ball moving?
Aug
4
revised Why aren't all points on a rolling ball moving?
added 8 characters in body
Aug
4
comment Creating a structural dynamic model using only modal test data
I think I did this in college with an impact hammer connected to a computer which reconstructed the modal shapes. See youtube.com/watch?v=tBRjPN8m6zE
Aug
4
comment Creating a structural dynamic model using only modal test data
Isn't $\phi^\intercal K \phi$ a matrix with the natural frequencies in the diagonals. So you can construct this experimentally by finding said natural frequencies.
Aug
2
revised Is torque still a vector in 2 Dimensions?
edited body
Aug
2
answered Is torque still a vector in 2 Dimensions?
Aug
1
answered A metal block in a tub of frictionless ball bearings
Jul
30
comment Why spinning a pen makes it easier to remove it from the stand?
Is there suction created when not spun?
Jul
30
comment What happens to the kinetic energy of a dropped ball when it comes to rest on the ground?
Did you hear that BAM? Is the sand hot afterwards? Did you have to wear goggles to prevent sand grains getting into your eyes?
Jul
30
comment Ball flying towards me or me flying towards ball
Maybe an equation that shows that force/impulse is a result of "relative momentum" (however you define that) would improve the answer.
Jul
30
comment How can we account for a friction force changing sign in a conservation of energy equation?
If there is friction, how is there conservation of energy?
Jul
30
comment Rotation matrix of Euler's equations of rotation relative to inertial reference frame
I thought you don't integrate $\dot{R}$ directly, but integrate the euler angles (and their derivatives).
Jul
30
comment Rotation matrix of Euler's equations of rotation relative to inertial reference frame
It is all explained here: cs.cmu.edu/~baraff/sigcourse/notesd1.pdf
Jul
30
answered Conical train wheels
Jul
29
revised Is there a situation where $\left|d\vec{v} / dt\right|$ is non-zero while $d|\vec{v}| / dt$ is zero?
deleted 19 characters in body