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visits member for 4 years, 5 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.


12h
comment Moment of Inertia Calculation
Disc MMOI is $I=\frac{m}{2} r^2$
12h
comment Moment of Inertia Calculation
Please look up "mass moment of inertia" for basic shapes and add them up using the "parallel axis theorem".
2d
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
2d
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
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 Simple question. Where to find coefficients of friction?
You search by material, not by application. Terracotta would be a ceramic material (clay). Try again!
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 $v(x)$
Apr
22
comment Torque considered about different points in a system
The edit needs to be rejected. I clicked the approve button by accident.
Apr
21
comment Large deflection of cantilever beam
Do you measure deflection along a fixed axis, or does it follow the arc of the end of the beam?
Apr
21
comment Instant centre of rotation for two connected gears
Is O fixed in space and A orbiting around?
Apr
20
comment Energy needed for Superman to take off and fly at the speed of sound
From your first two statements you have $4.0 + 0.2 = 4.8$ ????