Physical Definition and 1000 Threads

Homework Statement I've gone out and measured my changing weight in an elevator using a bathroom scale, taking measurements each second, with the elevator ascending 4 storeys. I am wondering if it is possible to work out the acceleration of the elevator from these results, and if so how they...

i have some question about lagrangian ...here are those 1) what is the physical meaning of L=0 .. from wiki ..i have found .."The Lagrangian, L, of a dynamical system is a function that summarizes the dynamics of the system." that means when L=0 ..the system has no dynamics ..as far as i...

Hi =D I was thinking about the physical units (g, m, s, K, J, A, V, etc). I know we got a thing in physics called dimensional analysis, so you analyse some variable that you know it depends on other variables and the two sides of the "equation" (I mean a equation with the proportional sign...

My understanding of a modern computer is as follows; 'information' is sent from a keyboard as current (I), this signal is sent to the CPU via the appropriate buses (in this instance, USB -> North Bridge -> main bus/cpu bus -> CPU), which is then recognized by a CPU via integrated circuit, and...

I am wondering if there is a physical interpretation of the Laplace operator (also known as Laplacian, Δ, ∇2, or ∇·∇). From my impression a gradient of a function is the vector field in the direction with the greatest change. Also a divergence is volume density of flux from a point source...

I would like to know how can parity be physically interpreted :confused:?

the physical meaning of the PDE?! Homework Statement http://agentsherrya.jeeran.com/qu.JPG Homework Equations How can I know the physical meaning of the following partial differential equation?!

I have so many fundamental questions about physics, i hope they are not considered "speculative" and deleted... Physics convolutes things so much, i wonder what does physics define as a physical property. For instance - an electron has a property (quality) of charge. Hopefully - this means...

Hi, Would appreciate any help anyone has for me. I am building a physical pendulum of sort, which consists of a hollow cylinder, which I am going to fill with sand. I am going to let the sand flow out of the pendulum and investigate the change in period with changing mass. I also am...

I have always been confused by SR and GR in terms of what each observer observes of their own frame of reference. e.g. Does an observer moving at a high v/c measure length contraction in their onw F of R? I assume not since all apparatus would be similarly contracted. Nor do they measure...

As though they also have a mental disability?

Hello, Is anyone here interested in oceanography? I'd like to do some independent research on undersea geomatics and digital mapping. In addition to a review of basic physics and a reading up on physical oceanography, what would be a good regimen of reading material to get me up to speed? I'm...

I'm doing some senior research into caching algorithms. In order to effectively evaluate some of our algorithms it would be amazing if we had access to physical addresses sent from the CPU to the memory captured in real time under real operating conditions. Does anyone know of a place that might...

Question Details: A 1.44 kg monkey wrench is pivoted at one end and allowed to swing as a physical pendulum. The period of its motion is 0.860 s, and the pivot is 0.290 m from the center of mass of the wrench. (a) What is the moment of inertia of the wrench? 0.0767 kgm2 If the wrench is...

What kind of air or water pressures can a human withstand? Approximately when does it become difficult to breathe and eventually impossible to breathe? After this point, would the person being succumb to these extremes be able to hold air in their lungs? What would be the first factor to cause...

Can man-made EM waves produce physical vibrations of objects? Can man-made EM waves vibrate powders like sand or talc? I'm trying to understand if any types of electronic frequencies can cause physical vibrations...thanks.

I don't understand why an x boost followed by a y boost is different from a y boost followed by an x boost. Surely only the resultant velocity matters, and isn't time reversal a symmetry of SR? Similarly, why is the matrix for three simultaneous boosts any different from the product of boosts...

Hello all, I've just started a class in physical chemistry and it seems to be progressing fairly slowly so I thought I'd start a thread so we could discuss some key concepts that are frequent in physical chemistry. Keep in mind I haven't taken any courses in thermal dynamics yet so I am...

This is not a homework problem, I'm going over some notes and seem to have a discrepancy. In a local region with no charge, del.E=0. Since the divergence is zero, there are no sources and sinks (ie charges). In my notes I have; "In cartesian co-ords, a solution of del.E=0 is a uniform...

Just curious, are there any?

it's konwn to all that laplace equation in 3 dimentions have clearly physical meaning,how about that in higher dimentions? I first thought that had something to do with relativity or quantum mechenics with higher dimentions ,but it is hard to figure it out . can anybody explain that ,thanks a lot

The quotes below (in blue) are from another thread https://www.physicsforums.com/showthread.php?t=364893&page=5" , but since they are a slight digression from the topic of the original thread, I have decided to continue the conversation in this new thread. Yes, that it what I am talking...

Hello How are u ? please help me What is Physical Principle for CT ( Computed Tomography ) ?

what actually happens physically ...when we make transpose of a matrix...and in unitary transformation we transpose the matrix and take the conjugate...physically what type of change happens in it.

If the universe is shown to have angular velocity, is this evidence of a physical universe prior to the "Big Bang"? Several studies are being undertaken currently to determine the rotational velocity of the universe. So far they have all indicated a positive velocity although the values...

What is the physical meaning of raising/lowering indexes? From a mathematical standpoint, I clearly understand what an expression like v_a = v^bg_{ab} means. But let's assume that v^a is, say, a 4-velocity: can I say that v_a is a 4-velocity as well? Or is it something different? Not to...

I have recently been reading on the topic of the philosophy of relativity and the nature of spacetime. An interesting example of the difficulty of understanding the physical reality of the relativity of simultaneity has me very much at a loss to explain how the theory of relativity really...

Hi to all, I've to write differential equation for desciribe system in attached file. The system is intended: from force f as input to position x2 as output. Initial condition are the following x1=0 and x2=0. In the attached file I've included all formula for descrive relationship between...

1. Homework Statement Hi, I've been thinking about a formulation regarding "physical quantities" (that is, the quantities that specifically constitute the object of measurement for Physics), energy, and the conservation of energy. It would be very helpful for me that you could confirm me...

Homework Statement a hoop of radius R=.18m and mass=.44kg is suspended by a point on its perimeter. If the hoop is allowed to oscillate side to side, what is the period of oscillation? Homework Equations I=MR^2 plus an offset? MR^2 so I=2(MR^2)? PE=1/2kx^2 w=(2pi)/T KErot=1/2Iw^2...

The metric due to the gravitational field of a spherical mass is described by the schwarzschild metric ds2 = c2 (1 - R/r) dt2 - (1 - R/r)-1 dr2 - r2 d\Omega 2 Where \Omega is the solid angle, and R is the schwarzschild radius. What are the physical meanings of the coordinates t and r...

Physical state to subjective "Qualia" and evolution - why? I'll try to make the points I'm getting at as concise and clear as possible. We all have sensations/emotions of pain, joy, hot, warm, cold, fear, curiosity, and the direct senses of light, sound, etc. Let us for the moment...

Hey all! Just a very short question: May I interpret the Lorenz invariant quantity \bar\psi\psi as being the probability density of a fermion field? Thanks! Blue2script

What effects do the physical properties (size of atom etc.) of an elemental metal have on the threshold frequency for that metal? I haven't been able to find a correlation between a physical property and the size of the threshold frequency myself; maybe I haven't looked hard enough, or maybe...

We keep searching for the Physical Laws but is anyone looking for the Laws that brought them about? Is it not inconsistent to expect Physical Laws to have no cause? Foundations of The Quantum Logic

Homework Statement A uniform disk of radius R = 1.40 m and a 6.0 kg mass has a small hole a distance d from the disk's center that serves as a pivot point. What should be the distance d so that this physical pendulum will have the shortest possible period? Homework Equations T =...

This is the question i have to answer... And i really need help with it! Please help me=) If equal masses of iron and water absorb the same amount of energy, then which one of them will have a smaller temperature change? Thank u! Daniel!

Homework Statement A long, straight, and massless rod pivots about one end in a vertical plane. In configuration I, two small identical masses are attached to the free end; in configuration II, one mass is moved to the center of the rod. What is the ratio of the frequency of small oscillations...

Hello I want to ask for something I have a theory and I want to write the equations for this theory How can someone invent a physical equation? I didn't find any sites on the internet Are there any resources about equations and their philosophy? Thank you

Books to build "physical intuition" All physicists say that it is very important to have this thing called physical intuition. I have a general idea what it means but I don't quite fully get the subtleties between physical intuition about a topic in physics versus understanding the equations...

I know that placing a paramagnetic molecule inside a magnetic field will induce a magnetic force on the molecule from the unpaired electrons, but what will the effect be on the physical properties on the molecule (of any?) Specifically will the size of the molecule be changed? My understanding...

Can someone please explain to me why it is that the direction of a cross product is perpendicular to the plane of the original vectors? What is the physical significance of this? I mean, if I take torque as an example, what the hell does it mean to say that the direction of the torque is...

Homework Statement Can anyone verify what a physical quadrapole looks like? I'm trying to do a multipole expansion on one Homework Equations I understand what a physical dipole is and how to do a multipole extension on one The Attempt at a Solution My best guess is that a physical...

When I take the fft of a set of data and plot it, there is a reflection around the nyquist. Everybody knows this, but I would like to know what the physical meaning of the second half (the reflected half) is. The real component is the same as the first half, and the imaginary component has...

Physical Chemistry Barometric Derivation! Homework Statement Derive an expression for the barometric equation that takes the temperature dependency (To=T-az) into account. Where To=ground level temperature, T=temperature at an altitude, a=proportion constant, z=altitdue Homework...

Hi, I've used complex numbers before for contour integration, circuit theory, and analysis; the only problem is, I have no idea how to think of complex numbers, physically - no teacher, book, or website seems to offer me any adequate solution. Can anyone please help me ? I hate doing...

Calculate the final temperature of a sample of carbon dioxide of mass 16.0g that is expanded reversibly and adiabatically from 500mL at 298,15K to 2.00L. I know the answer and understand how to do the problem except for 1 part. The equation to get the solution is : Tf = Ti (Vi/Vf)^(1/c)...

this is one of my pchem class homework... and I have no idea how to solve this... compute \tau for and electron in the double square well potential of width L = 2 Bohr, and depth \bar{V} = 4 and separation R = 3. Use atomic units for your computation... and in his lecture notes... he gave...

Hi! I would appreciate your thoughts on something. :smile: Let's say you have a ring with radius R rotating with angular velocity \omega about a vertical axis. A little bead is threaded onto the ring, and the friction between the bead and the ring is negligible. The bead follows the ring's...

This is a quick question. Is it correct to say that the change in color of iron to a reddish-brown color when the iron rusts is a physical change?