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  1. R

    Clarification needed: u-sub requires combining 2 constants

    Homework Statement Evaluate ∫-x/(x+1) dx Homework Equations The Attempt at a Solution I do a U-sub u=x+1 du=dx x=u-1 -∫(u-1)/u du -∫[u/u - 1/u] du -∫1 - 1/u du -[∫1du - ∫1\u du] -[u - ln(u) + C] ln(u)-u+C ln(x+1)-(x+1)+C ln(x+1)-x-1+C I combine -1 and C into a single C to get...
  2. R

    Artificial Gravity Centrifuge

    Is this true if the craft travels along the axis of the hoop?
  3. R

    Artificial Gravity Centrifuge

    Why would you need two rotating parts? You could just put two opposite facing rockets positioned on opposite sides of the craft. Start em up, wait until the adequate rotational velocity is reached, then shut em off.
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    Kenneth Krane's Modern Physics muon example (SR)

    I meant 3.0e^8 because final equation involves using 2.2us. Doesnt that require the answer to be two sig figs? 0.999978c = 2.999934 E8 m/s Which should be rounded to 3.0 E8m/s (due to the 2.2us) Actually, I knew the problem was simplified in the half life aspect. :-) Thanks for...
  5. R

    Kenneth Krane's Modern Physics muon example (SR)

    This is the frirst SR problem in his book. I think the question is flawed. The solution assumes a speed of 3.00 E8 m/s to calculate Δt=333us since it traveled 100km. Next, 333us and 2.2us is used to solve for velocity using the time dilation formula. Velocity is reported to be .999978c...
  6. R

    Does michio kaku hate leonard susskind?

    Hard to argue with logic like that!
  7. R

    Deja Vu Theory / Some Direction Needed

    Can we stimulate these areas of the brain to induce feelings of deja vu or love? Do we know what causes these hypersynchronous or hyposynchronous firing of neurons?
  8. R

    An infinite, isotropic, homogeneous, and static arrangement collapses under gravity?

    Ok, that makes sense. Thank you for the reply.
  9. R

    An infinite, isotropic, homogeneous, and static arrangement collapses under gravity?

    How can I make sense of that then? Newton's logic seems flawless to me.
  10. R

    An infinite, isotropic, homogeneous, and static arrangement collapses under gravity?

    This is what my intuition tells me. This is the quote from Hawking that confused me: So, the qualifiers are that the stars must be "roughly uniformly" distributed? It seems strange to not further clarify...especially when he says they will "always collapse."
  11. R

    An infinite, isotropic, homogeneous, and static arrangement collapses under gravity?

    Can anyone explain this to me? If we have an infinite amount of balls arranged in a kind of cubic matrix, in an infinite and static space...how the heck would that collapse on itself due to gravity? Thanks folks
  12. R

    IR from atoms

    I think we are talking about different things. To help determine the identity of an unknown chemical, we can do an IR analysis. We shine IR radiation through a chemical, and the bonds between atoms will absorb IR radiation at specific wavelengths. I don't know about atoms giving off IR...
  13. R

    IR from atoms

    is this true? In chemistry, IR spectra show bonds, not individual atoms... Like Useful nucleus said...the wagging, etc. of the bonds.
  14. R

    Universe expansion logic ?

    If light cannot reach us from the unobservable universe, then nothing can. Therefore, nothing we ever do can have any effect on the unobservable universe, and vice versa.
  15. R

    Relative velocity inside a train

    Someone get this kid a skateboard :-)
  16. R

    Meiosis-Number of chromosomes

    After DNA multiplication in a fertilized cell, the DNA molecules and mass will double....so 2m and 92. This is referring to S-phase replication, before mitosis. There might be something tricky about the number of DNA molecules, but I think what I said is correct.
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    Using images off the web for a report?

    I had to chuckle at this:tongue:
  18. R

    Macroeconomics problem

    A reserve requirement is a percent of cash a bank must keep in relation to its deposits. For example, if a guy deposits $100, the bank must keep $12, and can loan out the other $88. Securities are assets the bank owns, like shares or bonds. They can be sold like anything else to bring in...
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    Entrance to graduate programs

    I suppose a better way to ask my question is to say : Would it be "ok" if I were to forgo the electives and other classes required for a physics degree, and take the required mathematics and physics core? My uni requires: Cal I-III, and DiffEQ Physics I and II Modern Analtical...
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    Entrance to graduate programs

    Because taking classes for university credit costs me 1000 dollars per class and if it postpones my entry into a graduate program later than it could have been, then I would obviously rather avoid it. I'm not trying to avoid physics. I'm trying to avoid university credit for physics. That was...
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    Entrance to graduate programs

    Because I dont want be a post bach for another 3 years?
  22. R

    Entrance to graduate programs

    I am not looking at physics graduate schools, as I am nowhere near that point. I am looking into the path I need to possibly persue a graduate degree. Ie. what is required for application? What must I do should I choose to persue this? I WAS looking to go to medical school. That is why I am at...
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    Entrance to graduate programs

    I am in a strange spot. My undergraduate degree was in Business Information Systems (non-technical). I returned to the university 2 years ago to complete prerequisites for medical school. I am finishing in 2 weeks with A grades in all classes since returning. So, my physics exposure has been...
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    Entrance to graduate programs

    I have been searching for the requirements for entry into physics graduate programs. I am seeing GRE + physics GRE + 3 LORs Is it understood that the student has a strong background in physics or mathematics or do they really not require it? I have signed up for higher mathematics...
  25. R

    Viscous forces under freefall

    Interesting problem. I'm too dumb to answer.
  26. R

    Academic Advice (MD)

    Do we have to get technical? :eek: My point was that nobody will care about a 3.9 with no MCAT. A 3.9GPA and 90th percentile MCAT score will in no way "guaranteee" a slot. Average is 3.7 and a 90th% MCAT is very high, well above the average MCAT of a matriculant. Premeds drastically...
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    Academic Advice (MD)

    Are you looking to attend an US medical school? There are a few, I think, who do not require an MCAT score, although I'm sure it would hinder your application a great deal. A straight program???? What? You won't be special with a 3.9 GPA. We all have those. Just take the MCAT like everyone...
  28. R

    Apple vs. Earth - Gravity

    m1 = mass of Earth m2 = mass of apple r = distance between them G = gravitational constant The magnitude of force F will be the same for both objects, only in opposite directions. Everything is the same.....except mass (ie. inertia) If the mass of the apple is increased an incredible...
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