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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.


Aug
22
revised Find a central force given the orbit
added 650 characters in body
Aug
22
answered Find a central force given the orbit
Aug
22
comment Find a central force given the orbit
Those are spherical coordinates and not polar. Since there is no dependence on $\phi$ I suppose $F_{\phi} = 0$?
Aug
22
answered What is our estimated running speed on Moon's surface?
Aug
21
comment Kinematic sign convention
There is a convention that makes gravity potential negative, and thus moving towards the center of the earth is towards negative.
Aug
21
comment Kinematic sign convention
If positive is downwards then initial velocity or initial height has to be negative. Are you shooting downwards or upwards?
Aug
21
comment Kinematic sign convention
Please use Math Notation for readability.
Aug
21
comment Spherical coordinate versor problem
Use your right hand, with the thumb and two digits to create an orthogonal coordinate system to visualize the cross product.
Aug
21
comment Which way does the scale tip?
It does not matter. Only $B_2$ contributes to the weight on the scale. Replace the chord on the left side with a solid rod and see that the Buoyancy is an internal force.
Aug
20
comment related to projectile motion
Hmm, the exact same question got posted a few minutes ago and closed. Now show how you arrived at these equations, and fix the units on equation 4.
Aug
20
revised related to projectile motion
Some formatting for readability
Aug
20
comment Which way does the scale tip?
Buoyancy acts upwards on the spheres (purple arrows) and its reaction acts downwards on the beakers.
Aug
18
revised Massive ropes and tension
added 141 characters in body
Aug
18
answered Massive ropes and tension
Aug
18
comment Massive ropes and tension
Is $m g$ the total weight of the rope, or an additional hanging weight on the lowest point?
Aug
15
comment Do objects rotate around the torque vector or its center?
Note that if a pure torque is applied on a connected body (part of chain of bodies connected with joints) then it will rotate about the effective center of mass. That is the point where if a force is applied the connected body will purely translate.
Aug
15
comment Which way does the scale tip?
Actually there would be buoyancy on the rod, and it's reaction would contribute to the right side being pushed down.
Aug
14
comment Reduced mass and harmonic mean
Harmonic mean is like adding resistors in parallel. Effectively you are adding conductance $1/R$ terms. With reduced mass you are adding mobility $1/m$ terms.
Aug
14
comment Calculating torque in 3D?
Did you know that if only pure torques are applied on a rigid body (such that sum of forces is zero) then the body would rotate about it's center of mass. To rotate a body about an axis away from the COM you have to apply a net force.
Aug
14
awarded  Good Answer