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visits member for 3 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.


Feb
10
comment Mechanical system modeling
If spring $K_2$ is attached to mass $m_2$ on one end why isn't appear in the equations of motion for mass 2? Think about what elements apply forces to each isolated mass using two Free Body Diagrams
Feb
10
comment Mechanical system modeling
In the diagram the damper force is $D_1 \dot{x}_1$ but in the equations you use $Ba_2 \dot{x}$. And you need to decide and show which way is positive displacements & forces and which way negative.
Feb
4
comment Force when acceleration is zero
This is duplicate but I can't find the original yet.
Feb
4
revised Acceleration at two points on a rigid body
added 415 characters in body
Feb
4
answered Acceleration at two points on a rigid body
Feb
3
reviewed Approve suggested edit on Earth's graviational pull at the centre
Feb
3
comment Rigid body problem
If there is no friction then the rotation of the ring is irrelevant.
Feb
3
answered Rigid body problem in 2d
Feb
3
comment Rigid body problem in 2d
You have not specified the orientations of the bars.
Jan
31
answered Mechanical pulse reflection
Jan
31
comment Energy transfer in elastic collision
To figure out which way the momentum transfer goes look at this answer physics.stackexchange.com/a/80906/392. Momentum transfers in a such a way as to keep the final relative velocity on the opposite direction from the initial relative velocity.
Jan
31
comment Energy transfer in elastic collision
possible duplicate of Newtons Cradle, Collision Theory
Jan
29
revised Motion of rigid body system in absense of work
added 76 characters in body
Jan
29
comment Can a mass matrix be asymmetric?
@adipro only the symmetric parts contribute to the KE. It is like this transformation happens internally $M \rightarrow \frac{1}{2} ( M + M^\top )$
Jan
28
comment Can a mass matrix be asymmetric?
You're right. I added it as an answer.
Jan
28
answered Can a mass matrix be asymmetric?
Jan
28
comment Can a mass matrix be asymmetric?
In the world of robotics and dynamical systems the mass matrix is always symmetric. It is also positive definite, a result of kinetic energy $$K=\frac{1}{2} \dot{q}^\top M \dot{q}$$ being always positive.
Jan
28
comment Centre of instantaneous rotation problem
In the plane there is a point and in 3D there is a screw axis (see answer below). The point in 2D is where the 3D screw axis intersects the plane of motion. You can get to all the planar relationships from projecting the 3D problem down to a plane.
Jan
27
comment Centre of instantaneous rotation problem
Related post: physics.stackexchange.com/a/88597/392
Jan
27
revised Motion of rigid body system in absense of work
added 362 characters in body