Trouble Understanding Replacement for Radii in Proof Problem

[batman394]

THis is more of a proof problem. I worked the problem up until the point where it begins a replacement for r/R.

The book has enough examples to understand it up until that point.. but then it jumps from radii to simply the n term.

I got a copy of the solution from the professor and I just don't get why they do that. I can't integrate that function in any way to get that new n-based equation.

Any ideas on what's going on? I can't find anything in the book on that.

 

[batman394]

so we've sort of got it figured out.. the inner radius is r. the outer is R. the n in the system is just the ratio of the centerline velocity, and average velocity. relate that to the r and R.
and you can have n = r/R = u(bar) / u(c) ... and do a replacement and then do integration by parts.. and it all works out.. eventually.. the intergration by parts was a pain.

 

[piercas]

As a fellow scientist, I understand your frustration in trying to understand this proof problem. It is not uncommon for textbooks or professors to skip steps or make assumptions that may not be clear to students. In order to fully understand the replacement for radii in this proof problem, it may be helpful to review the previous examples and make sure you have a solid understanding of the concepts and equations being used. Additionally, it may be beneficial to reach out to your professor or classmates for clarification and to discuss the problem in more detail. Sometimes, having a different perspective or explanation can help make things click. If you are still having trouble, there are also online resources and forums where you can ask for help from other experts in the field. Don't be afraid to ask for help and keep persevering, as understanding and solving complex problems is a crucial part of being a scientist.