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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.


Apr
27
comment Moment of Inertia Calculation
Disc MMOI is $I=\frac{m}{2} r^2$
Apr
27
comment Moment of Inertia Calculation
Please look up "mass moment of inertia" for basic shapes and add them up using the "parallel axis theorem".
Apr
27
answered Units of eigenvectors
Apr
26
comment Average force for repeated elastic collisions
If you apply math formatting with $...$ it would make the question so much more readable. See physics.stackexchange.com/help/notation
Apr
26
answered Does it take more energy to open a door when applying force close to the hinge?
Apr
25
comment Does it take more energy to open a door when applying force close to the hinge?
I was going to say the question was not well formed, but it just got edited and my concearns have gone away.
Apr
25
comment Working out length of taut rope orbiting the earth remaining straight and radially directed
$2r$ ? Isn't that the definition of midpoint?
Apr
25
revised Working out length of taut rope orbiting the earth remaining straight and radially directed
added 4 characters in body
Apr
25
revised Does mass distribution/center of mass affect free fall?
added 547 characters in body
Apr
25
answered Does mass distribution/center of mass affect free fall?
Apr
24
comment Paradox in applying Newton's second law
Similar to this situation, when a pure torque is applied to end of an articulated chain of rigid bodies and it rotates about a point, this point is the effective center of mass. A force through that point will purely translate the last body of the chain.
Apr
24
comment Infinite series of derivatives of position when starting from rest
Yes, the trick is that the derivatives are almost like step functions. See plot from Wolfram Alpha.
Apr
24
comment Paradox in applying Newton's second law
There are two laws of motion. One relates net forces to linear motion of the center of mass, and the other the net torque about the center of mass to the rotational motion of the entire body. See possible duplicate link above for more details.
Apr
24
comment Paradox in applying Newton's second law
possible duplicate of Object Pushed by Multiple Forces
Apr
24
comment Infinite series of derivatives of position when starting from rest
This function has derivatives that look like a dirac delta function near zero. Essentially they provide an "impulse" to get things going as the value of the derivatives approaches infinity near $t=0$.
Apr
24
comment Infinite series of derivatives of position when starting from rest
Is this because $\bf{e}$ is a transcendental number and thus the derivatives don't loose order.
Apr
23
comment Computing Acceleration in mass and pulley system using conservation of energy
See people.fas.harvard.edu/~djmorin/chap6.pdf
Apr
23
comment Particle moving under force $F=-cx^3$
See this answer for how to handle non uniform acceleration cases.
Apr
22
comment Can a car get better mileage driving over hills?
Typical losses on a car (like a/c running, and rolling resistance) could easily amount to 6 kW of loss.
Apr
22
comment Can a car get better mileage driving over hills?
Acceleration curves (blue) should be labeled $\dot{v}(x)$ and not $v(x)$