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1. Desperate for astrophysics help

The energy generation rate for p-p fusion has an approximate dependence on density and temperature given by: E= e (p/pc)(T/Tc)^4 i don't know how to write all the symbols so in the above: E is epsilon, e is epsilon at the centre of the star, p is the density, pc is density at the centre...
2. Spectra Troubles

I have tried working on this the last few days, but have been unable to decide what is going on. I know there must be an easy way to do this, but for some reason i am stuck. Any help? Thanks
3. Spectra Troubles

Consider the Lyman photons for Hydrogen-like atoms with Z greater than one. Which of these atoms have Lyman alpha photons in the 1)visible 2)UV 3)X-ray and 4)gamma-ray parts of the spectrum? Can list ranges of values of Z in the answers. My thoughts are to use 1/lambda=...
4. Absolute zero founder

sorry don't know much about Wikipedia. is it reliable? you know how you can't be sure of some of the things you read online.
5. Absolute zero founder

This is a pretty straight forward question. Does anyone know who exactly first determined the value of absolute zero and when it was. I am getting conflicting information about it. this is not a question i have to answer, just a little bit of information i would like to include in a physics...
6. Astrophysics - Can there be a contact binary from white dwarfs

Question: A typical white dwarf has a mass of 1 solar mass and a radius of 10 thousand km. A typical neutron star has a mass of 1.5 solar masses and a radius of 30km. Given that there's a natural speed limit in Nature, namely the speed of light, is it possible to have a contact binary...
7. Integral help

just wanted to let anyone who helped out with this know that my friend and i figured out, by looking at the derivative of the answer the prof gave, that there is a typo in the original question. it should not be 5x^3 (1+x^2)^1/2, but 5x (1+x^2)^1/3. it was written in such a way that i don't...

9. Integral help

does anyone agree with me that maybe the answer given by my friend's sheet is incorrect?
10. Integral help

sorry, but i'm not sure how your answer is equivalent to the answer she was given ie)15/8(1+x^2)^4/3 +C. also, i guess i wasn't clear in my last post. they haven't done trig subs, by parts, partial fractions, etc, nothing like that yet. all they have done is u subs. this isn't even my...
11. Integral help

wow. that is unlike either answer i posted. i guess i should have stated that the only special way they have learned to solve integrals is with a u sub. did you see what exactly i did wrong in the way i tried to solve it? sometimes one needs an extra pair of eyes to find the error.
12. Integral help

this should be easy, but i'm struggling. i'm trying to help a friend solve: integral(5x^3(1+x^2)^1/2), sorry i don't know how to do the integral sign. i did a u sub with u=1+x^2, du=2xdx and u-1=x^2 so: (5/2)integral((u-1)(u)^1/2) i get (1+x^2)^5/2-10/6(1+x^2)^3/2 +C the...
13. Theory question

this is probably a stupid question, but what exactly qualifies as macroscopic ie)what is the actual range? also, i get the question now. it was much simpler than what i was trying to make it out to be. thanks for the imput. you physics guys rock.
14. Theory question

so the size of macroscopic objects is much larger than what the uncertainty in their positions. i'm not sure what this means in regards to quantum mechanics. i find quantum physics so confusing and i highly respect anyone who understands and enjoys it.
15. Theory question

i have a question where it asks me to find the uncertainty in a ball's postion (m=50g). i have that part all figured out, but then it asks me what the answer indicates about the relevance of quantum mechanics to macroscopic objects. (the answer was approx. 10^-32m, a very small uncertainty)...
16. Double slit electron experiment

isn't dsin(theta)= (m+1/2)lambda for the dark fringes of the double slit. how do i know to use this instead of just dsin(theta)= mlambda? also, again, i don't understand where you got the tan equation. it has been a very long time since i did anything with diffraction, and i have one of...
17. Double slit electron experiment

i have no clue as to where you came up with dsin(theta)=(m+1/2)(lambda) also what does the tan equation mean. i need some help to understand what is going on. what is delta y? i am so lost on this topic. any layman's terms explainations would be so appreciated. thanks.
18. Double slit electron experiment

i think i understand what you are saying for c). the text describes a similar situation, where the detecting particle has uncertainty in its momentum and postion. through calculations they determine that for the dectecting particle: (delta P)(delta y) < h/2. this is a clear violation of HUP...
19. Double slit electron experiment

A monochromated beam of neutrons (speed 0.40 m/s) is directed through a double slit with 1.0 mm separation. An array of detectors is placed 10m from the slit. a)what is the de Broglie wavelength of the neutrons? b)how far off-axis is the first zero-intensity point on the detector array...
20. Physics HUP help

i just realized that i kept repeatedly using the same wrong number to figure out the other question. now i get it exactly right. thanks for your input on the my original question. guess i'm not as lost as i thought. thanks.
21. Physics HUP help

p=0.05kg * 30 m/s = 1.5 kgm/s. 1.5 kgm/s * 0.1% =0.0015 kgm/s (delta x) > h/(2Delta p) where h is h bar ie) h/2pi delta x > 6.626*10^-34/ (4 *pi* 0.0015) delta x > 3.52*10^-32 like i said, i tried this method with another question, but i gave the kinetic energy and a 5% accuracy...
22. Physics HUP help

honestly i haven't figured out where to start. i can get momentum by multiplying the mass and the speed. i wanted to multilpy that by 0.1% to get a delta p value and then solve for delta x. this is the method i used for other questions, and i did not get the right answer. also i am not...
23. Physics HUP help

A ball of mass 50g moves with a speed of 30 m/s. If its speed is measured to an accuracy of 0.1%, what is the minimum uncertainty in its position? What does this answer indicate about the relevance of quantum mechanics to macroscopic objects? I am completely confused. My prof just gave us...
24. Parametric equations for particle motion

Describe the motion of the particle with position (x,y) as t varies over the given interval. x=2+cost y=3+sint where t is greater than or equal to 0 and less than or equal to 2 pi i've tried to eliminate t and came up with y=3+sin(arccos(x-2)) i don't know if...
25. Power series representations

the problem is that i only know how to get the power series rep for the arctan x part of the integral. i can't figure out how to get the representation for the whole thing. once i have that sorted out, the radius of convergence should be simple. any advice on how to solve the rest of the...
26. Power series

that is the integral, thanks, but i am not sure what to do after pulling it apart into two integrals. quite honestly, i am puzzled by this whole topic. any advice?
27. Power series

Evaluate the indefinite integral as a power series and find radius of convergence. (i don't know how to type the integral and summations signs, sorry) (integral sign) (x-tan^-1x)/x^3 dx. ( if you write this out it makes more sense) i was able to find the power series of tan^-1x =...
28. Power series representations

Evaluate the indefinite integral as a power series and find radius of convergence. (i don't know how to type the integral and summations signs, sorry) (integral sign) (x-tan^-1x)/x^3 dx. ( if you write this out it makes more sense) i was able to find the power series of tan^-1x =...
29. Leslie Cube (still)

thanks for your input on this. glad to here i did it correctly, and of course i converted to kelvin, thanks for the heads up though
30. Leslie Cube (still)

sorry, this was my question from yesturday, and now my assignment is due tomorrow. anyone have any help for me? A Leslie cube has a surface temp of 97C. One of its four side faces has an area of 100 cm^2 and is painted black. Calculate: a) the wavelength at which the spectral intensity...