Natural Definition and 1000 Threads

As I understand evolution, with natural selection, nature kills the weakest, for an example predators killing the slowest in a herd of Antilopes. What I don't understand is how life could have evolved into something as complex as us in only 2.5 billion years. I've heard of epigenetics, but that...

how do we find the natural frequency of a tower of a wind turbine if, say, the tower is circular hollow cross sectional shape (its not tapered or anything, just cylindrical all the way up). I think i know how to find it when we're ignoring its weight, but what is it when weretaking into account...

How can i solve that equation: x^2 + y^2 = z^2-1 or x^2 + 3y^2 = z^2?

Do we have at present any knowledge whether our natural constants (gravity constant, Planck's constant, ...) are rational or irrational numbers? Thanks, Trinitiet

Hello everybody, I have a question about the undamped natural frequencies for a three degree of freedom system. The equation of motion for the undamped system is : M\ddot{x}+K\dot{x}=0 The undamped natural frequencies I found is a complex number ...

Homework Statement A certain spring elongates 9mm when it is suspended vertically and a block of mass M is hung on it. The natural frequency of this mass-spring system is: a)0.014 b) 5.3Hz c) 31.8Hz d) 181.7 e) need to know M x=9mm mass=M Homework Equations I don't know any...

Homework Statement Hi. I'm trying to work out the undamped natural frequency of a cantilever beam. The setup of the system is shown in the image below. http://www.flickr.com/photos/56901717@N03/5249378659/ Data:(all lengths measured from the hinge on the left of the beam) Beam...

I've been asked to express the inverse hyperbolic secant function arcsech in terms of the natural logarithm and am unsure as to where to begin in solving such a problem? could someone please point me in the right direction?

Homework Statement My homework problem is the double integral of y/1+xy dxdy. It is a definite double integral and both integrands have the values of a = 0 and b = 1. Homework Equations Integration by parts: uv - int(vdu) The Attempt at a Solution My first step of the double integral is I...

Hello, I am taking a vibrations course and we are currently talking about using PDEs to find responses of beams. In the book, there is an equation to find the natural frequencies of a simply supported beam under an axial load: omega = (pi^2/l^2)*sqrt(EI/roA)*sqrt(n^4 + (n^2*P*l^2)/(pi^2*EI))...

Homework Statement Solve the compound interest formula for t by using natural logarithms. Homework Equations A=P(1+\frac{r}{n})^{nt} The Attempt at a Solution I start by dividing both sides by P. I then take the natural log of both sides and end up with ln(\frac{A}{P})=nt *...

ok i need some clarification if you have a circuit where a current source is in parallel with an inductor a resistor and a capacitor is this considered a natural response or a step response. I guess i thought a step response is if a switch is switched and a source is added then it is a step...

Hi everyone, I'm a beginer in communication science. I have very fundamental question. We know that natural radio waves are emmited from sun to Earth (as a part of their electromagnetic spectrum); what will happpen if our communication devices uses radio waves of same frequency and wavelength...

Homework Statement Use Natural Logarithms to solve for x in terms of y y = \frac{e^{10x}+e^{-10x}}{e^{10x}-e^{-10x}} Homework Equations I am not too sure. The Attempt at a Solution I multiplied both sides by the denominator first. Then I multiply by an LCD of e^{10x} I end up...

I think there are only two primary languages, i.e. natural language and mathematical one, which we use to communicate . If we go one step further, then I would say even mathematics is a subset of natural language where we use symbols and other signs to represent our concepts, ideas into...

Homework Statement Find mass of vibrating steel cantilever. It is fixed at one end and got a mass on the other (free) end. Find the mass required when it is vibrating at w(natural) = 1800 rev/min. Lenght: 50mm width: 7mm Thickness: 1mm Homework Equations w = sqrt(k/m) The...

Homework Statement Given G =U −TS+PV −BaM show that S(T,Ba,P) = -(dG/dT)Ba,P Homework Equations The Attempt at a Solution I know how to proceed if there are two variables and attemped to use this giving dG = dU - TdS - SdT +PdV +VdP - BadM -MdBa Using central...

How do I start to evaluate this integral? \int\frac{1}{\ln x}-\frac{1}{(\ln x)^2} dx I tried subbing u=\ln x but I'm getting no where... The answer is [tex]\frac{x}{\ln x}+C[/itex] If I differentiate the answer, I get the integral easily, but the reverse... I'm having trouble figuring out...

I am doing a small physics research project introducing sound, resonance, and natural resonance frequencies, but I have questions. I know that resonance is the tendency of a system to oscillate with larger amplitudes at some frequencies rather than others. Does this just mean that the...

Today I went along my uncle to get the natural gas cylinder refilled. He uses it at his farm. When the refilling man placed it on the weighing scale it weighed, let's say, 7 kg. During the refilling process the cylinder was placed on the scale. Once he removed the refilling pipe after the...

Homework Statement I have a linear elastic spring with spring constant E, The spring is mass less, and is held fixed at the left terminal and has a mass m attached on the right terminal. We can neglict gravitational forces. Find the natural oscillation when the tension sigma = E*epsilon...

we all know the mass are attract to another mass so i want know if there are studies and assays to understand really what are the mass

Alright, admittedly I'm a noob at LQG, but I have a basic question. The cosmological natural selection, as I understand it, is that universes are born from singularities (or something close) inside of black holes and 'bounce', inflate, and become universes like our own. But what spawned this...

Multiples of natural frequency?? Hi all! I am a little confused. Why will an object not resonate with multiples of its natural frequency? I think due to the reason that through its multiples, it will not return (even if temporarily) to its natural state...am I mistaken?? Thanks in advance...

What happens if the frequency of the forced oscillation is Pi / 2 radians out of phase of the natural frequency of the spring mass system? I guess this makes the amplitude of the spring mass system to oscillate at a maximum amplitude.. Am I correct? Thanks in advanced..

A letter in the current issue of Nature: ==quote== A two-solar-mass neutron star measured using Shapiro delay P. B. Demorest1, T. Pennucci2, S. M. Ransom1, M. S. E. Roberts3 & J. W. T. Hessels4,5 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, Virginia 22093, USA...

Not sure if I've posted it on the correct thread but I don't think this classifies as advanced physics! I'm currently doing a physics assignment where we have to choose an energy source for a town in Australia (Broome). I am choosing to use a combined cycle gas turbine with natural gas as...

Does natural selection apply more to information in general than just to genetics?

Lets define D1(n) to be the first digit of a natural number n, e.g. D1(571) = 5, D1(119) = 1, ... Naturally one would expect that all digits come with the same probability 1/9, but looking at it in more detail one finds rather counter-intuitive results. If one counts these digits and...

Homework Statement Let (xn) n ∈ N, be a succession. Construct a function F: [0,plus infinity[ to Rn (if possible continuous) whose restriction to the naturals is (xn) n ∈ N, ie xn = F (n) for all n ∈ N, and such that ∃ limx → + ∞ F (x) = L if and only if ∃ Limn → + ∞ xn = L The Attempt at a...

I was trying to figure out the relation between the equation of a discharging capacitor and the Natural Inverse Exponent function v(t) = Vo*e^(-t/rc) A*e(-Ct)+B I get that A represents the voltage and the C is the inverse of the time constant but i can't figure out what the B stands for

Since my late interests have been related to networks, I've started a pet project focusing on natural numbers network. I wanted to share my early explorations with this community since you have the proper background to interpret the results. I chose this network exactly because compared to...

Homework Statement prove the identity. ln csc(x) = -ln sin(x) The Attempt at a Solution With a calculator I am able to prove it is in fact an identity, but I have NO clue why? In fact I am quite unclear on logarrithms in general as my algebra class just barely covered them and...

IQ is supposed to be the measurement of your "natural intelligence." IQ is supposed to be the measurement of your "natural intelligence." However, can your IQ vary on how much brain activity you're doing? For instance, during the Summer a person is lazy and not doing any studying or anything...

Is Card (N even)< Card (N)? Where N even is set of all even Natural numbers, N is set of all Natural numbers. Hint: use the mapping from N eve→Nn N even to N is given by n-->n a. Show examples of this mapping from N even N even to N. b. Is the mapping above onto? One-to-one? My try...

Homework Statement Heat transfer due to natural convection in a rectangular enclosure with vertical walls that are at different temperatures. Need a correlation for Nusselt number that could handle an aspect ratio A (width/height-ratio), A > 100 and Rayleigh number Ra > 10³. Also, Prandtl...

Homework Statement Let T be a family of finite subsets of the natural numbers N = {1, 2, 3,...} such that if A and B are any members of T, then the intersection of A and B is nonempty. (a) Must N contain a finite subset F such that the intersection of A, B and F is nonempty for any sets A...

Does this thing works?

So I am not quite sure how to solve for x here. 1.2E-21=(.3567)(ln(x/.175))

Homework Statement Show that if n belongs to N, and: An: = (1 + 1/n)^n then An < An+1 for all natural n. (Hint, look at the ratios An+1/An, and use Bernoulli's inequality) The Attempt at a Solution I think i have a vague idea of what to do here, like I am sure induction is involved in this...

Homework Statement Every triple of consecutive odd natural numbers, with the first being at least 5, contains at least on composite. Homework Equations N/A The Attempt at a Solution I know from number theory that of every set of consecutive odd integers, one of them is divisible...

Hello.. Am an Electrical Engineer, my FYP concerns the artificial limbs... I made a small research about the nervous messages, and how it flows from the brain until it reaches the muscles. In the arm i found that there are 3 nerves (Ulnar, Median, and Radial nerve) which are responsible for arm...

I'm going to do a little popular-level talk for undergraduates (not necessarily science majors) on baby universes, cosmological natural selection, and Penrose's cyclical universe. The most recent substantive paper I have on CNS is this: Smolin, "Cosmological natural selection as the explanation...

Homework Statement Evaluate the integral when x > 0: indefinite integral of ln(x2+19x+84)dxHomework Equations I know I need to use some form of integration by parts: integral of u*dv=uv-(integral of(du*v)) The Attempt at a Solution I began by making u=ln(x2+19x+84) and dv=dx. Thus, (after...

the question is: differentiate wiith repsect to x: (ln(5x))^1/5 i differentiated and got : 1/5ln(5x) y'=1/5x I don't think this is correct. The answer should be ln5/5. Can anyone help me? chanella

Homework Statement ln(3x+1) = 3-lnx Homework Equations Solve for xThe Attempt at a Solution Well I put the ln on the left side ln(3x+1)+ln(x) = 3 Then I combine them ln ((3x+1)(x)) = 3 So I take e e^ln(x(3x+1)) = e^3 I get x(3x+1) = e^3 So I divide the x (3x+1)/(x) = (e^3)/(x)...

Hi All, I have been trying to understand some fluid mechanics in a research paper and have been wrestling with the mathematics for quite some time now without success. I want to derive gradient operator with following coordinate system in R^3 space Let and arbitrary curve C be locus of...

I have some questions about adsorbed natural gas technology to those who knows: 1)Could adsorbed NG be stored at high pressures? Such as 3600 psi? 2)What is difference in energy density between CNG and ANG at the same pressure?(3600 psi)? 3)What is way of adsorbed gas retreival?Do exist...

Seems like a silly question, but a search of the forum and Google and my online textbook yielded no results (*shakes fist at textbook writer). Please help?

what imean by natural is...u know how motts comes in regular and natural? well i bought the natural kind..but i bought store brand. if i wave my hand behind the bottle i can barely see it...(the shadow of it) with gatorade i can see it much clearer..but idont like gatorades... one site...