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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.


Nov
30
comment Projectile motion where gravity is a function of $y$
If $t(y)=-\frac{1}{b} \ln \left( \frac{y}{A} \right)$ for example then $y(t)=A \exp \left(-b t\right)$ is the inverse. But in this case $t(y)$ isn't an invertible function I think.
Nov
29
comment Projectile motion where gravity is a function of $y$
I think the point is you cannot come up easily with an equation and it is far simpler and more powerful to create a simulation varying distance and speed with each time step.
Nov
29
comment Projectile motion where gravity is a function of $y$
Related SO post stackoverflow.com/q/21983784/380384
Nov
29
comment Projectile motion where gravity is a function of $y$
the last integral yields $t(y)$ which you need to invert to get $y(t)$.
Nov
29
answered Projectile motion where gravity is a function of $y$
Nov
29
revised Forces exerted on legs of a table
added 947 characters in body
Nov
29
answered Forces exerted on legs of a table
Nov
29
comment Forces exerted on legs of a table
With three legs there is a unique solution that comes from the sum of the forces and two moment balance equations. Nothing ambiguous about it
Nov
28
answered What forces are at work in a loose ball bearing bicycle hub?
Nov
26
answered How to account for inertia in kinematics?
Nov
25
comment Calculating rotation using moment of inertia
What is slowing the spinning? You mention no friction, so what is removing energy from the system?
Nov
22
comment How much pressure do wheels exert on the ground?
The solution people employ is is discritizing the domain into little rectangles and using the Love/Businesq formula for deflection and pressure $$\delta = \frac{1-\nu^2}{\pi E} \int \frac{P}{|r|}\,{\rm d}A$$
Nov
22
comment How much pressure do wheels exert on the ground?
The actual distribution provides for infinite pressure at the ends (it follows a ${\rm asinh}(1/x)$ when $x \rightarrow 0$. So to get real-real you need to consider local plasticity and non-linear materials. Yikes!
Nov
22
comment How much pressure do wheels exert on the ground?
The reason a length value is needed is because the pressure distribution is assumed to be constant along the contact, then taking a small slice $\Delta x$ and applying the linear pressure $F/\Delta x$ yielding the width $b$. So the calculation assumes and infinitely long cylinder with linear pressure which is then trimmed to $\ell$.
Nov
21
comment Force and Torque being applied off-center due to magnetic forces
If you apply a pure torque on a (resting) rigid body the center of mass will not move. The body will rotate about the center of mass. Albeit, it is very hard to apply a pure torque (without a net force component). See physics.stackexchange.com/a/81078/392
Nov
21
comment Force and Torque being applied off-center due to magnetic forces
Is this 2D or 3D?
Nov
21
comment Force and Torque being applied off-center due to magnetic forces
A torque does not impose any additional forces. If you have multiple forces then you need to sum them up to get the motion of the center of mass. You also need the net torques (including the effects of force at a distance).
Nov
21
answered How much pressure do wheels exert on the ground?
Nov
21
comment How much pressure do wheels exert on the ground?
Or download en.vinksda.nl/toolkit-mechanical-calculations/… and enter your data.
Nov
20
comment How torque and friction cause wheel to roll
The answer is in the question. Motion is caused by the net forces and you only have one force acting in the horizontal direction.