Scale Definition and 743 Threads

hello std dev is the square root of the variance. assume we measure lenghts of something normally distributed. we use millimeter. we calculate our variance to be 100mm and thus std dev to be sqrt(100)=10mm but, if we instead would measure the same objects in meter, then we'd get the...

I would like to find out which functions retain the same structure when they are scaled. Particularly I am interested in projections. For example, a parabola 3d space viewed at another angle can still be represented by at^2 + bt+c. A circle however can not (ellipse) I am guessing conic...

Homework Statement Barbara has a mass of 60.0 kg. What would a metric bathroom scale (a scale that uses Newtons) read if she steps on it in the following situations: On the Earth in an elevator experiencing an acceleration of 3.0 m/s2 while speeding up and moving upward. Homework...

Hey, the coupling constant in QFT is scale dependent. This scale \mu, it seems to me, is a mathematical tool used to regularize the infinities that arise at the loop level. Thus physical quantities have to be independent of this scale \mu. This implies that the coupling 'constant' is a...

Can someone please tell me if I have done this correctly? "2 cylinders are similar. The area of the ends of the smaller and larger cylinders are 16cm2 and 100cm2 respectively. The height of the larger cylinder is 12.5cm. Calculate the height of the smaller cylinder." Firstly, if the scale...

Hi, Ive been readin about relativity, I am a little confused. The faster speed an object has, the faster time passes on the object. So how long does say a ray of light take to get from teh sun to the earth? It is ~8.5 of our minutes, but say I were on the ray of light; traveling with...

My biology teacher asserted to our class that compared to the vastness of the atmosphere of our earth, the amount of harmful gasses we are emitting is a fraction of a percent and therefore can be dismissed as harmless, and instead we should be worrying about more fragile ecosystems down here on...

Above what scale is the universe considered to be homogeneous? What sort of measure is used? I've looked at a few cosmology texts and they don't really discuss it much. Weinberg states 300 million LY. With 250 million LY diameter voids and 1370 million LY long filaments, 300 million LY seems...

Homework Statement http://j.imagehost.org/0069/thermo.jpg Homework Equations The Attempt at a Solution OK, so I tried to derive θ in respect to r as in θ(r): \frac{d\theta}{dr} = \frac{-100}{(r - 1)^2} Then, I multiplied both sides of the equation by 'dr', d\theta = \frac{-100}{(r -...

If you had an extremely sensitive scale (use your imagination) and shone a beam of light upon it, could you measure the force that the photons were exerting on the scale? would there even be a force?

I claim that an experimental demonstration of interference using single particles like photons is also an experimental demonstration of the validity of QM on the macro scale. The idea is that any which path information will destroy the interference pattern. Formally, the visibility of the...

What is the thermodynamics temperature scale, both in theory and in practice? Is it really independent of physical substance? Why?

so that visually everything appeared the same, could you use physics (e.g. gravity or something) to prove that you and everything else is bigger than it was before?

i have took a basic course in fluid mechanics: Bernoulli equation states that: P + (1/2)*ρ*v^2 + ρ*g*h = constant where P is the pressure , ρ is the density , g is the garvitational acceleration and h is the distance from the center of the Earth , and that constant is our reference. that...

Confirmation of general relativity on large scales from weak lensing and galaxy velocities. http://arxiv.org/ftp/arxiv/papers/1003/1003.2185.pdf

This is a general question, not requiring an equation. If I travel near the speed of light, I know my mass will increase. I am assuming my weight will increase, but since there is little gravitational pull, since I am not near any large objects, then my scale would say near-zero, if I stepped...

If you stand on a bathroom scale, the spring inside the scale compresses 0.50 mm, and it tells you your weight is 740 N. Now if you jump on the scale from a height of 1.2 m, what does the scale read at its peak? I'm guessing you use 1/2kx^2 but otherwise, I'm not sure.

Hi! I'm making a computer program that represents some quantities in a graph in this way: x'i=(xi-xmin)/(xmax-xmin) so that the possible values of x range from 0 to 1. This is a linear scale. I want to do the same with the logarithmic values of xi. That is, I want to implement a log...

Understanding the short-distance behaviour of gravity is crucial for constructing a quantum theory of gravity. The Newtonian inverse square law approximation has been tested in laboratory down to millimeter scales, but I'm not aware of any laboratory scale experiments testing general...

Hello, I did a wind tunnel test of a rectangular box with equal sized louvered window at the inlet and outlet. This box is a scale model and representative of a typical room with windows for cross-ventilation. I measured the velocity inside the room. Now I want to calculate the Reynolds...

Homework Statement the gas scale temperature is defined as: T=273.16 lim Ptp->0 (P/Ptp) The bulb of a constant volume gas thermometer is immersed in an ice-water-vapour mixture and the recorded pressure is 0.500 atm. It is then immersed in a boilng liquid and the pressure is 0.720 atm...

Hi all, I am about to begin my studies as an experimentalist and I keep hearing about these terms when someone represents his data as histograms. Can some one here, please, give me a clear explanation about their meanings. My background is theory and you can use as much mathematics as you...

I was going through few books and i found out that piezoelectric concept generates good amount of current but not enough power(wattage) ... As I was thinking of making a project on this concept can somebody tell me how can huge amount of voltage as well as current be generated from piezoelectric...

I know because E=(n+1/2)*h-bar*omega , and n is an integer , with the integers ranging from zero, to all positive values. Photons are said to be massless physical quantities and according Einstein's theory of special relativity (or general relativity) mass and energy are equivalent. So if a...

Planck energy: E_P = m_P c^2 = \sqrt{\frac{\hbar c^5}{G}} Gravitational radius: r_G = \frac{r_s}{2} = \frac{G m_P}{c^2} Gravitational radius is equivalent to Compton wavelength: r_G = \overline{\lambda}_C \frac{G m_P}{c^2} = \frac{\hbar}{m_P c} Planck force is a constant in the Einstein...

Hello! If I have the gaussian function, but x is a loarithmic scale. Can I infer that, if x was plotted using a regualr scale, that the function would be 'fairly' linear? At least initially? As the rate of change gradually increases befor slowing down again. I think this is reasonable... I...

In the movie Speed a speeding bus is shown jumping a long gap in the elevated freeway. The Mythbusters test the physics at 1/12 scale. In the TV show Grant writes an equation to find the scaled down ramp exit velocity, where supposedly one must compensate the small scale speed downward because...

Could someone explain the relationship between the FSC and the Planck Scale? What are they in relation to each other. I know what the Planck Scale is, and I even have a loose understanding of the FSC, but what of them in contrast and comparison? And how does the FSC affect QM, if at all...

Homework Statement Draw a clearly labelled “Minkowski spacetime” diagram illustrating two events ((1) a farmer firing his laser gun at his cow, which is sitting along his positive x-direction, and (2) the cow dying) as observed by two observers (S at rest in the farmer’s and cow’s frame, and...

Hello All, I'm currently working on a project to help with a local spaghetti bridge contest. I'm trying to build a scale of sorts from a plate that is supported at each end. Picture a bracket "[" but with the two legs on the ground. I'm using strain gages on the bottom in the shape of...

Hi I have to perform a fitting procedure on a semi logarithmic scale but I'm not sure how to weigh the experimental data points. I'm studying the decay of the luminescence of a certain type of crystals and the function I'm using has the form I = \frac{1}{\tau} e^{-\frac{t}{\tau}}...

hi, if we drop a piece of meat say 1kg from 1m above the plate, on a plate 2kg, and the plate is on a weighing scale of spring F=kx, how do we find how much the spring will first compress? ( not referring to the equilibrium where total weight = spring force) so we can't use F=kx = mg here...

So whose quantum gravity theory will crash-and-burn if this is correct? http://physicsworld.com/cws/article/news/40834 Zz.

Um, I suppose this is very basic but I just got kind of confused. Okay suppose you are standing and swinging a rope with a mass attached to its end, so that the circular trajectory of the mass at the end of the rope lies in a vertical plane. And suppose you are stood on a weighing scale. Does...

Homework Statement I want to try to find the scale height of a planet using H=kT/Mg, where H is the scale height, k is the Boltzman constant, T is the surface temperature, g is the acceleration of gravity, and M is the mean molecular mass. I am having a great deal of trouble understanding...

Hello, I have been trying to make a parametric plot with logarithmic axes in Mathematica, but have been unable to find an option to do this. Can someone tell me how to do this? My code is below, and for reference, EnergyScint[b] is the Bethe-Bloch equation for energy deposit for a fully...

Hi, I would like to know something about the possibility to convert data set into z-scores to ensure a common scale for analysis. More specifically, when this conversion is needed and why. I am working on motion data (from 3 persons) tracked from video and I can use a common reference for...

Homework Statement You use a spring scale to pull a 1.5 kg object on a horizontal frictionless surface with a constant horizontal force of 1.3 N (according to the scale reading). You use a stopwatch to time how long it takes the object, starting from rest, to cover a distance of 2.7 m. What is...

I want to create a plot, but want the horizontal axis to have increments as multiples of pi eg. {0, pi/2, pi, 3pi/2, ... } Is this at all possible in matlab?

Hi, I'm currently looking into reflectivity and emissivity of metals in sunlight. However, I can't quite grasp how the mechanisms of reflection and emission differ. Emission obviously occurs because an electron is exited by a photon and then is de-excited and emits photon or photons. However...

Homework Statement Let's say you are given 10 identical springs. How would you develop a scale of force (i.e., a means of producing repeatable forces of variety of sizes) using these springs? Homework Equations None that I can think of. The Attempt at a Solution My guess is that...

Homework Statement Hi guys, I have a question on problem 4.11 in Kleppner and Kolenkow's mechanics book. A chain of mass M and length L is suspended vertically with its lowest end touching a scale. The chain is released and falls onto the scale. What is the reading of the scale when a length...

http://img233.imageshack.us/img233/5816/espaotempoquntico1.th.jpg Two pictures of quantum spacetimes... The theory of quantum gravity (LQG) can perform calculations and predictions on the concrete structure of space and time at the Planck scale. Equations formulas that describe...

CMB fluctuations and large scale fluctuations nowadays do not match ? The CMB dark matter density fluctuations for big scales is d_rho/rho~ 10^-5 and lower. The scale factor increased ~ 1000 times from last scattering to now. Linear perturbation theory predicts that the density fluctuations...

In his book THE BLACK HOLE WAR, 2008, Leonard Susskind makes the following comments around page 135-137: In the following he happens to be referring to a Planck scale cube...let's ignore that specific geometric shape... (Later in the book of course he describes his holographic...

Can you think about relativity in terms of the motions of atoms as they are subject to intermolecular forces? Is time moving slower for the atom which is accelerating with respect to another? Or, would the macroscopic averaging negate the individual motion of the atoms? Or, is this a...

Homework Statement Give an argument for there being a connection between scale length and frequency Homework Equations scale length = (wave length) / (Length)The Attempt at a Solution So from only my physical intuition I'm coming up with the longer the scale length the longer the wave length...

I don't quite understand why macroscopic objects we encounter in everyday life don't exhibit quantum probabilistic behavior. For example, the car standing in front of my house has a definite position and definite boundaries rather than being dissolved in some cloud where it's not clear whether...

Hello all! I'm a sophomore in college and the only real lead I have so far is becoming a teacher. I had an awesome high school physics teacher and decided during my freshman year in college that I want to teach college physics. Currently, I'm on track for a B.S. in Physics. Further on I plan to...

Homework Statement A beaker with water is in equilibrium with a certain weight in a balance. Then we tie a cord to a stone, and soak the stone in water, without touching the bottom. What will the balance read and why? http://dl.getdropbox.com/u/698994/ilustra%20forums/experiencia%20empuxo.png...