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bio website dotancohen.com
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age 37
visits member for 3 years, 10 months
seen 3 hours ago

Jul
9
asked Pressure loss after water goes up and back down 7 stories
Jul
9
comment Cannon on spacecraft: hitting yourself
Thank you, you perfectly describe the mechanical system as I perceived it.
Jul
9
comment Cannon on spacecraft: hitting yourself
@Alfred: Not quite! You are thinking if the projectile is shot in the same direction as the space station. However, if the new velocity vector has an equal tangential component to the original and a zero radial component, but a different inclination, then it will still be in a circular orbit. This is known as an inclination change. It is how we have geostationary satellites launched from ~30 north of the equator!
Jul
8
comment Cannon on spacecraft: hitting yourself
Actually, this is a great answer as it does mention why there is doubt. As to the idea that shooting behind leads to a lower orbit and shooting forward leads to a higher orbit, the "in between" that you are looking for is to release the projectile with quasistatic separation speed from the space station. They will then orbit together.
Jul
8
asked Cannon on spacecraft: hitting yourself
Jul
4
accepted Does water in the drain follow the distance-squared rule of force?
Jul
4
comment Does water in the drain follow the distance-squared rule of force?
Looking at the spinning soap this morning, in fact the center was spinning (angularly) faster than the outer edges. I don't have a way of measuring the linear velocity at each distance, but it certainly wasn't spinning as a solid body!
Jul
3
comment Might a planet perform figure-8 orbits around two stars?
Thank you. Following the links in those threads, and googling one broken link, I found this gem of an orbit.
Jul
3
answered Why are there more vertical takeoff than horizontal for spacecrafts?
Jul
3
asked Might a planet perform figure-8 orbits around two stars?
Jun
29
comment Does water in the drain follow the distance-squared rule of force?
Thank you John. Linear variation sounds to me as though the soap is spinning as a solid mass, which in retrospect does seem to be the case as I don't notice the shape changing as it spins. How then do the spiral arms form?
Jun
29
revised Does water in the drain follow the distance-squared rule of force?
deleted 17 characters in body
Jun
29
revised Does water in the drain follow the distance-squared rule of force?
added 14 characters in body
Jun
29
accepted Is the environment around an asteroid harsher than in interplanetary space?
Jun
29
asked Does water in the drain follow the distance-squared rule of force?
Jun
27
comment Do observers at different speeds perceive other speeds differently?
And things get even more interesting as the train and/or ball approach the speed of light!
Jun
19
comment Can a planet have a larger diameter than Jupiter?
@M.Na'el: Smaller: less diameter. More massive: more mass. In the same sense that Mercury is smaller but more massive than Ganymede.
Jun
18
awarded  Nice Question
Jun
18
comment Can a planet have a larger diameter than Jupiter?
svn copy -r 42 system://solar Jupiter is just complaining Unrecognized URL scheme for 'system://solar'. What is the URL scheme to get the old version?
Jun
18
comment Can a planet have a larger diameter than Jupiter?
I see, thanks. That sounds like a sound method.