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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.


13h
comment Calculating rotation using moment of inertia
What is slowing the spinning? You mention no friction, so what is removing energy from the system?
1d
comment What is the force required to move an object between two stationary objects?
Is the fit and slip fit, a press fit or a loose fit? Putting something of size $a$ into a hole of size $a$ is not enough information as the tolerances on the hole and the part effect the insertion force dramatically.
1d
comment Why is less force required to open a door when we apply a force at a greater distance from the hinge?
Yes, either a kick or a punch. Always at the 2/3 point with appropriate ha-ya sound.
1d
comment Why is less force required to open a door when we apply a force at a greater distance from the hinge?
An impulse is just a short lived force. If you target certain rotational acceleration, yes the longer the moment arm $\ell \rightarrow \infty$ the lower the applied force needed. But to minimize the reaction forces at the hinges you need $\ell = \frac{2}{3}L$. Hence the most efficient comment in terms of power ( force and distance).
1d
comment Why is less force required to open a door when we apply a force at a greater distance from the hinge?
The axis of percussion is a distance $\ell = c + \frac{I}{m c}$ from the hinge. $c=\frac{L}{2}$ is the center of mass distance (from hinge), $I$ is the mass moment about the cm and $m$ is the mass. For a door $I=\frac{m}{12} L^2$ and hence $\ell = \frac{2}{3} L$.
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 Why is less force required to open a door when we apply a force at a greater distance from the hinge?
The most efficient way to open a door is to kick it $\frac{2}{3}$rds the way away from the hinges. That is where the percussion axis is.
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.
Nov
20
comment Damping Constant for a Ball Rolling in a Bowl
The link is course notes from Carnegie Melon. I do not know who the author is, or what the course# this relates to.
Nov
19
comment What is the true weight in the geostationary satellite?
mass is $10/9.83$ at the poles.
Nov
19
answered Damping Constant for a Ball Rolling in a Bowl
Nov
19
comment Car driving / falling off of a cliff - will it land upright?
If you notice the vehicle rotates and to end. There is nothing stopping it from rotating, so overall it might land any which way. Sort of like a coin toss.
Nov
16
comment Will a stone thrown in space move forever?
Well there are super voids out there en.wikipedia.org/wiki/Void_(astronomy)