quantities Definition and 191 Threads

Hi I have a simple question what is the conserved quantity corresponding to the symmetry of galilean invariance? and Lorentz invariance? cheers M

Hi, Do anyone know how I could make vector quantities in Microsoft Word 07, for example something like F = ma, I want a vector notation on F and a. Please be as specific as you can. Thanks

Does anyone know of any sites where I can buy components like ICs or off-the-shelf stuff like resistors and capacitors in small amounts (<10, for example?). The only one I know of is jameco.com, and they don't have one of the ICs I'm looking for (LM2678T-12). Any others?

Hello, What is the physical meanining of rational and irrational numbers? In the same sense, what is the physical meanining of complex quantities? Thanks in advance

Hi Just wondering if someone can tell me if the following are scalar or vector quantities and why Current Potential Potential Difference Also, I'm wondering if we include plus/minus signs in calculations depending on the charge. Ex. would current be negative if it was a negative...

http://news.yahoo.com/s/livescience/20090722/sc_livescience/strangehumansglowinvisiblelight Weeird! But awesome.

Homework Statement how can i have a feel of pressure ... i mean how much is 1 psi and how much is 10 psi pressure ... can you please give an example ! Homework Equations i think pressure = force / area but still i don't undersatnd how much is 1 Newton ... i mean i don't get a feel of...

1. In still water, a student can swim at 1.2 m/s. She swims perpendicularly across a 40 m wide river, landing 30 m downstream. In crossing the river, what distance does the student move? 2. d=df-di, cosine, sine, tangent 3. Again, i tried drawing out a picture. I made 40m the x...

i have problems converting quantities, like for example Km/h to metres per second, or Days to seconds. I realize it involves multiple multiplications or division but for some reason i still have trouble with this relatively simple concept. In some cases, i even get the final answer wrong because...

I'm currently taking several physics courses (mechanics, thermodynamics etc) and common to them all is their frequent use of infinitesimals. I'll just give a short recap of how I was taught calculus, and this is how my math teacher would word it: [calculus training] \frac{dy}{dx} is not a...

Does dark matter form orbits around stars ? Why would dark matter and "regular" matter, say, a dust belt not mingle and stick together? Just with black holes, with d.matter we are positing new objects with complex properties instead of simply admitting imperfection in gravity. Since it is...

Hi everyone. This is kind of a geometry/quantum mechanics question (hope this is the right place to post this). So, in quantum mechanics we consider operators that reside in an infinite dimensional Hilbert space (to speak rather informally). We even have the cool commutator relation, which is...

Hi everyone, I need your help badly. This may sound simple to everyone but I need to get the concept sorted out. For ratios, we know that it is a comparison between 2 or more quantities with the same units. My question is, can ratio be used to compare between say ingredients in a...

i wondered at the idea that calculus works for continuous functions and in reality fundamental quantities are discontinuous. For example energy or an electron can't asume all values. Therefore isn't there a conflict when we work on a equation like dE/dt or something similar which involve...

in the equation *C^12+C^12-->Mg^24+y(+13.93 MeV)* for what quantity is the energy assigned? and how would i plug in a certain amount of carbon?

Use the Fourier series technique to show that the following series sum to the quantities shown: 1+1/3^2+1/5^2+...+1/n^2=pi^2/8 for n going to infinity I foudn the series to be: sum(1/(2n-1)^2,n,1,infinity) but I don't know how to prove the idenity. I don't know how to go about...

[SOLVED] Conserved Quantities Question answered!

Hi all. I would like to know what's so special about those "integratable systems"? I heard that KdV and NLS models belong to these systems and so they have soliton solution? But why? What's the importance of this? And what's the significance of many conserved quantities? I know, say, KdV has...

I know that if a particle is in a spherically symetric potential its angular momentum will be conserved, but what about if somehow we manage to produce say an elliptically symmetric potential? Will the particle then have a momentum along the curve of the ellipse conserved? Thanks

Please tell me if there are motivated physical reasons to consider that combinations of dimensionless physical quantities that appear at the exponent of e in distribution functions have the same magnitude in all inertial reference frames in relative motion, Thanks in advance

Hmm... I don't know the differences between the scalar and vector quantities? Help, please? I don't want to fail physics!

Hi, in my physics book (serway) they say "dimensions can be treated as algebraic quantities" but I don't understand this very well. If I sum meters I get meters, if I multiply meters I think I get meters^2 because the area of a rectangle is b.h. But if, for instance, I multiply seconds.seconds...

Why are Planck quantities considered to be maximum and minimum quantities - Planck distance etc ? If they are,then,since in calculus a maximim/minimum is given by,for example,dy/dx = 0,then,for example,y = Planck quantity when x = some other quantity.But what is x?

No, I am not going to ask you what the difference between those two are. =P I know the differences, but at the beginning of this term, my class started to learn about electricity and magnets, and that stuff. Now, vector quantities are those that have direction and scalars are those without...

i would like to ask a question about what does quantities and dimension mean in this sentence is it possible for two quantities to have the same dimensions but different units? thanks a lot in advance

I understand that the quantities E^2 - B^2 \vec{E} \cdot \vec{B} (the dot is vector inner product). where E and B are the electric and magnetic components of an EM wave, are invariant under Lorentz/Poincare transformations. Can someone explain the physical significance of this ? Is...

Electric toothbrushes can be effective in removing dental plaque. One model consists of a head 1.10 cm in diameter that rotates back and forth through a 70.0 degree angle 7600 times/min. The rim of the head contains a thin row of bristles. Part A: What is the average angular speed in...

Since antiparticles have reversed proper time, can I conclude that all invariants are reversed for antiparticles?

Express the following quantities as an ordinary decimal number: a) The sun has a diameter of 1.392 * 10^6 I get 1392000. b) 8.4*10^-6 I get 0.000084 Is this right

hi, if i have mass possesses potential U(x)=-Gm1m2/(x^2+y^2+(kz)^2 )^1/2 , i said angular momentum of z is conserved but not angular momentum of x , y .. is it correct ? what else is conserved ? energy ?

My girlfriend had this problem on her first tutorial sheet at Univeristy. She is doing maths. I am doing physics and was interested in the answer. It asked what the result was when a displacement vector was added to a velocity vector. The vector addition can obviously be done on these two...

i have no idea how to do excess and limiting (mole conversions) does this concept even apply to this Question and how to figure out this out? if 10 g of ammonia gas reacted with 5 g of Oxygen gas, what mass of water is produced? using this eqn: NH3 + O2 --> NO2 + H2O

Recently, I was thinking about this: Am I right if I say that there are only 4 (and exactly 4) basic physical quantities which are enough to explain all observed phenomena in nature? (of course I mean HOW, not why) (for example length, time, mass and electric charge or current)...

Hi, I just want to share my curiosity in the definition of 4-vector quantities such as world line 4-vector x^alpha, 4-velocity vect, gauge potential etc. the ones with subscript for indices usually have the first component with negative sign and the ones with superscript for indices have all...

Hi everybody, I just want your opinion in some questions: First of all, how do we define a physical quantity? Is it a mathematical creation that helps us describe something happening in nature? And all these formulas that we have come up with: example F=dp/dt . Are they mathematics or...

I'm curious about something - What quantities in physics do you think are "defined" quantities, i.e. quantities which are defined in terms of other physical quantities and therefore are not required? e.g. momentum is defined as p = mv, velocity is defined in terms of space and time, i.e. v =...

In the Halliday-Resnick textbooks, there is only mention of strength of a magnetic field, which in SI units is the derived unit Tesla. However, on my TI-89 and on more modern sources on the internet (including a Fuji-film PDF!), there is mention of the unit of the Oersted for magnetic field...

The Haber's process facilitated the production of chemical fertilizers such as ammonium nitrate and has a dramatic impact on crop yields. Since the 19th century, average crop yield per hactare have increased almost five fold for cron and eight-fold for wheat. However, runoff from fertilized...

general "quantities in chemical reactions" questions hi, im in high school, and we are currently doing a unit of chemistry on quantities in chemical reactions, and there are a few things i don't get, and i was wondering if anyone could show me a formula or an example, on calculating the...

We all know the speed of light has a absolute value in vacuum measured by all observers from various reference frames and itis the fastest speed in the universe. My question here is, if there is a limitation on how fast matter would travel, is there also a limitation on how slow matter would...

In my text, it says that the conservation laws alone do not suffice to predict the motions of two particles if the collision occurs in two dimensions. It is generally required that we know one of the final quantities in order to predict the rest. Does this mean that it is impossible to predict...