Recent content by rexregisanimi

Guys, this isn't a difficult question but it does test our ability to communicate precise concepts. Here's the Physics: We make a free body diagram of the forces on the plane: before the engines or conveyer belt turn on, there is a force pulling it straight down onto the ground (gravity)...

Mr. Jones has a good recommendation as well. No matter which book you choose, be sure you follow each step. Do a few problems at the end of each chapter or section to be sure you understood and can apply what you read. It takes patience and time (but not a whole lot of money) but it will be...

Excellent end to your post! I love the "heavenly body" comment :) Many things look like each other and sometimes our minds like to connect them together because of it. A transformer and a galaxy are not related in any significant way but to model a galaxy in your mind as a transformer to...

I think we're all confused why a galaxy seems related to an electrical transformer. Perhaps you could explain what you mean? The motion and arrangement of stars in galaxies is deeply studied. It's really quite interesting!

Excellent video! Sanborn Chase, do you mean an electric transformer?

The stars are real but the arms in a spiral galaxy are not; as I stated, they are simply an illusion. I'd recommend An Introduction to Modern Astrophysics as a reference. It's in one of the later chapters if I recall correctly... (Think of where an oscillating particle spends most of its time...

Thank you for your replies. Why then isn't the second term zero? If we're just concerned about those values, shouldn't both terms go to zero?

One thing to keep in mind is that spiral arms in galaxies are "density waves" and not actual structures of the matter. They represent the area where many millions of stellar orbits reach their maximum distance from the galactic center of mass. At this point they are traveling the slowest and so...

So, in other words, the top triangular part of the F_ij matrix cancels with the bottom triangular part because of the Third Law; this leaves the diagonals only which are zero because a particle will not exert a force on itself. Is that correct?

I notice there has not been a post about the EM Drive on the website in quite some time! This surprises me considering it is such a widely discussed issue in the general public. With the recent peer-reviewed publication about the device, I thought there would be a lot more discussion aboutut it...

I'd highly recommend Carroll and Ostlie's book which you can find on Amazon here: https://www.amazon.com/dp/0805304029/?tag=pfamazon01-20 Be sure you understand Calculus at least to a basic level before embarking ;)

Hello everyone! I am reviewing the derivation of the Virial Theorem from an introductory Astrophysics book (Carroll and Ostlie's) and found a step I couldn't follow. I've attached a photo of the step. Can anyone explain how Newton's Third Law brings about eqn 2.41? I don't see how that first...

Sorry your first post took three days to get an answer! Can you not just look up the absorption spectrum for the Earth's atmosphere and compare that to Venus' spectrum? Subtract one from the other type of thing? Venus is just reflected sunlight with some absorption lines, etc... Perhaps this...

I was referring to examining stellar motion in the central parts of the galaxy. Examining the motion of stars in orbit around the central black hole and noting deviations, etc. should provide a start in getting the needed information... Do the NFW equations diverge when integrated from r=0 to...

Perhaps start by researching how one determines dark matter distribution around a galaxy and extrapolate downward :)