Physical Definition and 1000 Threads

  1. person_random_normal

    Physical significance of Enthelpy

    what is Physical significance of Enthalpy for a process where we don't have pressure constant
  2. robbertypob

    Can biological processes be explained using physical laws?

    Do we understand how the physical laws of the universe created biology? How can we explain cell division, consciousness, evolution, as a product of matter operating in a universe governed by laws?
  3. M

    Explaining a physical model (differential equation)

    Homework Statement Check on labb41.jpeg (I am not used to formatting my mathematical equations on the web, I can only format in my local text-editing programs). Homework Equations Again, check on labb41.jpeg The Attempt at a Solution I have plot the solution to U(I) as according to the...
  4. Aravind Raj

    Physical meaning of equations of equilibrium

    From the equations of equilibrium "σy+(∂σy/∂y)*(lower case delta y)" is the force acting along y direction. can anybody explain the physical meaning of the second part of the force where we multiply delta and del?
  5. J

    What would it take to fully simulate a physical system?

    Many people out there today seem to think that we'll soon have computers powerful enough to simulate the physical world well enough that we'll be able to upload ourselves and live in such a simulation. People really seem to think a Matrix situation is possible. Some, like Nick Bostrom, have...
  6. D

    What is the physical significance of Poisson brackets?

    I know the definition of the Poisson bracket and how to derive elementary results from it, but I'm struggling to understand intuitively what they are describing physically? For example, the Poisson bracket between position q_{i} and momentum coordinates p_{j} is given by \lbrace...
  7. sankalpmittal

    Compare Pendulum Angular Frequencies for Cases A & B

    Homework Statement A metal rod of length 'L' and mass 'm' is pivoted at one end. A thin disk of mass 'M' and radius 'R' (<L) is attached at its centre to the free end of the rod. Consider two ways the disc is attached : Case A: The disc is not free to rotate about its centre of mass, the...
  8. evinda

    MHB Is the physical law unit-free?

    Hello! (Wave) A small sphere with radius $1$ and density $p$ moves downwards with constant velocity $v$, under the influence of the gravity $g$, at a liquid of density $p_l$ and viscosity coefficient $\mu$. (The units of $\mu$ are mass per unit of length per unit of time). From results of...
  9. B

    Physical insight into integrating a product of two functions

    I was wondering what the physical insight is of integrating a product of two functions. When we do that for a Fourier transform, we decompose a function into its constituent frequencies, and that's because the exponential with an imaginary x in the transform can be seen as a weighting function...
  10. Riccardo Lardi

    The Aesthetics of impossible or unreal physical phenomena

    I know this may not be a typical question for the Physics board. I am a MA Design student working on a project to illustrate experiments on speculative/fictional physical events. My final work will consist of strongly simplified staged experiment lab situations and should touch on the imaginary...
  11. fian

    Physical meaning of KdV equation

    Here is one of the KdV form u_t + u_x + uu_x + u_{xxx} = 0 Where u is elevation, x is spatial variable, and t is time variable. The first two terms describe the linear water wave, the third term represent the nonlinear effect, and the last term is the dispersion. From what i understand, the...
  12. fian

    Physical meaning of KdV equation

    Here is one of the KdV form u_t + u_x + uu_x + u_{xxx} = 0 Where u is elevation, x is spatial variable, and t is time variable. The first two terms describe the linear water wave, the third term represent the nonlinear effect, and the last term is the dispersion. From what i understand, the...
  13. jk22

    Is every physical theory non physical

    I noticed that famous theories have a non physical part in them : Newtonian instantaneous forces Quantum particles going faster than the speed of light in schroedinger mechanics. This contradicts the maybe only physical theory that exists : general relativity. I thought the following...
  14. Quarlep

    A Physical Situation Which Physics Rules Collapse

    Whats the circumtances which physics rules collapse and don't work.Theres any explanation it to use mathematics. Here I don't mean singularity things.I know in singularity physics rules collapse I want to talk more generally.
  15. L

    S11 and Frequency Modeling for Physical Parameter

    Hi all, I am trying to obtain an empirical equation/model having 2 inputs (frequency and S11) and one output (a physical parameter) I have done various simulations using CST of the System and now I am trying to relate S11 and frequency to a physical parameter. Any suggestions of how I should go...
  16. N

    Difference Between Dimensional & Dimensionless Physical Constants

    Homework Statement What is the difference between a dimensional physical constant and dimensionless physical constant? Homework EquationsThe Attempt at a Solution
  17. MexChemE

    Energy balance -- Physical interpretation of Q

    Hello PF! I have a simple question on energy balances. Suppose you have an isothermal reactor where you want to have an exothermic reaction happening at 450 °C. The simplified energy balance for the reactor is Q = ΔH. Supposing ΔH = -150 kcal, then Q = -150 kcal. Does this mean that, a) in order...
  18. Coffee_

    Lack of physical understanding of Noether's theorem

    Let me first give a quick sketch of how Noether's theorem was stated in class and then explain what is not very clear to me. Consider for simplicity the Lagrangian of a single coordinate ##L(q,\dot{q},t)##. Now, if there exists a variation of the coordinate ##\delta q## for which at any time...
  19. R

    What is the physical meaning of the Thomas-Fermi vector?

    The Thomas-Fermi wavevector relates to the damping of an electric field caused by build up of carriers around an impurity (screening). But I can't understand it's physical meaning. Wiki states "Thomas–Fermi screening is the limit of the Lindhard formula when the wavevector (the reciprocal of...
  20. S

    Understanding Big R(t) in Astronomy: A Physical Perspective

    I'm having trouble with with understanding what this is, our text, Astronomy: a physical Perspective by Kutner, uses R(t). I understand r(t) is the distance between two objects at a point in time, but what is the scale factor big R(t)?
  21. D

    Sine wave relationship with physical waves

    This is probably pretty basic but I've never actually seen an explanation of how exactly the sine wave relates to the physical waves it is so commonly used to represent. Could it be imagined as like the periodic thumping of a speaker where the peak of the sine graph represents maximum air...
  22. E

    'Information' in computing vs. physical information

    Hey everyone. I'm sorry if I'm posting something irrelevant here. I really don't know where to ask this question but this hit me while learning Computing Principles (It's my first day in college). I'm one who is interested in physics too. Hence, I got a little confused about the term...
  23. binbagsss

    Curvature Singularity: Necessary & Sufficient Conditions

    For a physical singularity I think it is sufficient that anyone scalar quantity blows up, Why is it not a necessary condition that all blow up? For a curvature singularity am I correct in thinking that it is a sufficient condition to find a coordinate system in which the metric coefficient no...
  24. Abtinnn

    Mathematical Methods in the Physical Sciences by Boas

    I study in high school, but I know a fair amount of math (differential, integral, and vector calc., differential equations, linear algebra, etc.) Would you recommend this book if I want to pursue higher levels of math such as PDE's and Tensors and so on? Does this book explain things clearly...
  25. J

    Unbiased Physical Vapor Deposition

    I apologize if this seems ignorant, but I am at a loss and I need some assistance. I recently built a small vacuum PVD system (Ion source, argon, target material, substrate cradle, etc.) and was showing it to a colleague when it was noticed that my system was unbiased. It actually didn't occur...
  26. M

    Physical significance of Volumetric Flux

    Homework Statement I am just a little bit confused. I have a question that is asking me to explain what the physical significance of volumetric flux is. Homework Equations I am not sure that this problem requires any equations! The Attempt at a Solution I know that the flux corresponds to...
  27. F

    What are the physical implications of phonon softening?

    I am interested in how phonon softening would lead to changes in a crystals elastic properties but I don't understand what actually is the consequence of this. What would be affected by a reduction in energy to phonons in a crystal? My best guess would be a reduction in energy to phonons causes...
  28. G

    Determine all of the Physical Chemistry Variables of the System

    Homework Statement A weather balloon is filled with Helium gas and released from the ground. It goes up 18km and achieves a diameter of 15m. Determine if the following values are greater than zero, less than zero, or equal to zero: ΔV, ΔP, ΔT, ΔU, ΔH, Ssys, surr, Stot Homework Equations ΔU =...
  29. V

    Physical applications of Riemann zeta function

    Hi I was wondering if there any observations that have only been described using the Riemann Zeta function? What would it mean in physics to assign a divergent series a finite value? Thank you Edit Sorry I overlooked a thread just posted that asked about this so this might need to be deleted.
  30. M

    What is the volume of air swept out by a moving plywood sheet on a track?

    Homework Statement A rectangular 4 x 8 foot sheet of plywood is fixed to a sled which moves on a track. The face of the plywood is perpendicular to the direction of the track. The sled is pushed a distance of 3 inches. What is the volume of air swept out during this motion. Homework Equations...
  31. jasonleroy

    Phase Delay Changes with Physical Length Changes

    Hopefully I can word this correctly. Consider viewing S11 of a short on a smith chart. It starts at the left and moves clockwise around the edge. If you then add a small length of line between the reference plane and the short, the phase angle wraps further around the outside in the clockwise...
  32. A

    Books for deriving old physical formulas

    Hi dear forum members, I'm an undergrad. physics student(freshmen),i've learned that Galilei found g.t^2=s formula(a free falling object's position function with respect to time)without using physical foundations,by using him blood impulses for count time not utilizing acceleration etc,i've...
  33. L

    Physical Asymptote Homework: Trajectory y=x^4-x^2 & Limit y(x)=h

    Homework Statement For example particle performs a motion in x-y plane. In y there are walls from both side so particle can go in y direction from zero to h. I need to plot trajectory. If I got trajectory y=x^4-x^2 then \lim_{x\to \infty}y(x)=\infty[/B]Homework EquationsThe Attempt at a...
  34. P

    Medical What's the difference between mental and physical stress?

    I had a discussion with someone who studies psychology recently and she was referring to mental stress as of what I thought being called physical stress. Namely while she was talking about mental stress she mentioned stressors and hormones. So my problem: Stress = tension Physical =...
  35. HTHLAndre

    Proving Centripetal Acceleration Physically?

    How Can I Prove this Physically Homework Statement [/B] So I need to do a project where I prove centripetal acceleration. All the cases I've seen of where it's proved is using formulas, though I need an actual project. By an actual project I mean something like...
  36. Mr Davis 97

    What are harmonic oscillators and physical systems?

    My question is how we describe a harmonic oscillate. Wikipedia says, "a harmonic oscillator is a system that, when displaced from its equilibrium position, experiences a restoring force, F, proportional to the displacement, x." My question is, how is the harmonic oscillator a "system"? I thought...
  37. A

    Physical interpretation of Neumann-Dirichlet conditions

    I am working on a PDE problem like this: Consider the wave equation with homogeneous Neumann-Dirichlet boundary conditions: ##\begin{align} u_{tt} &= c^2U_{xx}, &&0<x<\mathscr l, t > 0\\ u_x(0, t) &=u(\mathscr l, t) = 0, &&t > 0\\ u(x, 0) &=f(x), &&0<x< \mathscr l\\ u_t(x, 0) &=g(x), &&0<x<...
  38. D

    Position and speed are enough in a physical system?

    I've recently read in this article http://www.en.uni-muenchen.de/news/newsarchiv/2013/f-m-77-13.html that "In the world of classical mechanics, the state of a physical system and its future evolution is fully determined by the instantaneous locations and velocities of its constituent particles"...
  39. C

    Physical meaning of a wave packet w/ respect to HUP&duality

    I'm a QM noob/newb trying to understand the physical implication of a wave packet, in my mind it is something like this: On the x-axis there is displacement (vibration), probability on the y. I Imagine stretching and compressing the wave packet. When I stretch it out, the amplitude must...
  40. THE HARLEQUIN

    Physical explanation of e^i*pi=-1

    Hi everyone , i was wondering for a while to get a satisfactory proof of the equation : e^i*pi = -1 yes , i know it can be derived from euler's formula ... which is e^i*x = cosx + isinx ( which can be proved using differential calculus ) so, e^i*pi = cos(pi) + isin(pi) ( which leads to the...
  41. rumborak

    Information as the key underlying physical principle

    It seems to me, at least when it comes to quantum mechanics, "information" has become the most basic unit. Like, quantum entanglement works to the point that information is extracted, and one can even revert certain things by making sure the information is destroyed. Same with the discussion...
  42. S

    How to extract physical meaning from differential equations

    Homework Statement I am given the following coupled differential equations: \begin{align} (r^2+1)\ddot{θ}+2r\dot{r}\dot{θ} &= u1\\ \ddot{r}-r\dot{θ}^2&=u2 \end{align} together with the following expression for the kinetic energy: \begin{align} T &= 0.5(r^2+1)\dot{θ}^2+0.5\dot{r}^2...
  43. arpon

    Physical significance of an equation of wave

    We can mathematically derive the equation of wave, \frac{\partial^2 y}{\partial t^2} = v^2 \frac{\partial^2 y}{\partial x^2}, where v is the velocity of wave propagation. Can we prove this equation physically (not just taking derivatives of the equation of wave, but making physical meaning in...
  44. T

    Help with Physical Vector problem

    This is a repost because i realized i put it on the wrong forum section. After getting Kleppner and Kolenkow's second edition textbook I began my exploration of physics. I'm a sophomore in high school and VERY ignorant in regards to physics so if this question make no sense set me straight. I...
  45. G

    How can we sure that physical laws are always the same in al

    How can we sure that physical laws are always the same in all the universe?
  46. T

    Physical realization of a system

    Hi! I have a simple question regarding the realization of systems. In my university course books, it's mentioned multiple times that a system with a transfer function G(s) is realizable, if the denominator's degree is at least that of the numerator's degree. I found the same statement on the...
  47. N

    Are Physical Waves Real Objects?

    Are physical waves, like sound waves, or water waves, real physical objects like matter?
  48. H

    To physical scientist, what do you think of biological sciences?

    I majored in neuroscience and applied math in college and want to do computational neuroscience research long term. Being at the crossroads of biology and physical sciences, I think a lot about how the two "worlds" view each other. The lab I'm currently in has some people directly from the...
  49. TheNerdConstant

    Could new physical laws be created for large systems?

    What i basically mean by this is that at this point in time we have classical and quantum physics, both need a different set of rules to describe their phenomenon due to the size of their appropriate systems why is this and does that mean we could also say the same for immensely large systems...
  50. N

    Is wave function a real physical thing?

    Is the wave function ( ex. electron wave function) just a mathmatical equation or a real physical object? I know that it's widely known that it's just an equation however some researchers say that they have proof that it's real. Here is the link...
Back
Top