Questions tagged [models]
DO NOT USE THIS TAG just because the involved physics is based on a model. All physics descriptions are inherently model-based. This tag is reserved specifically for addressing model development, validity, simplification, or other meta-model questions.
402 questions
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How do I model a cloud that is about to release a lightning using Gauss or Coulomb? [closed]
For context: I am working on a 10 min presentation on dielectric rupture for physics (1st grade) Hi, the problem with it is the distribution of charges, since it is not homogenous, I'm not able to ...
1vote
0answers
47views
Formula or Equation describing when two clamped sheets are pressed together [duplicate]
This question is about a physical phenomenon and so I would like to actually know the derivation of the shape as well as the formula. I was playing around with powder pillow packets, and regardless of ...
1vote
1answer
136views
Modeling a system to indirectly represent the dynamics of a ring on a string
Original question: A rope of length l (l>d) is attached between two walls (at the same elevation) a distance d apart; initially slack. A ring of mass m is threaded onto the rope, it forms a "V&...
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4answers
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A speed limit for static friction?
Suppose that a box is sliding along the floor, subject to kinetic friction and a pushing force (in the direction of its motion) that is slowly decreasing. The box is decelerating, and eventually the ...
- 475
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1answer
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What constraints must higher-dimensional models in physics satisfy?
Many theories in physics, such as string theory, M-theory, and extra-dimensional field theories, incorporate higher-dimensional spaces. I’m trying to understand the fundamental constraints that these ...
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How are physics formulas derived? [closed]
I was wondering how physics formulas are generally derived. I assume that they come from a variety of relationships, factors and observations. For example, the formula for centrifugal force would be: $...
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1answer
43views
Can the turbulent viscosity in Large Eddy Simulation (LES) be taken out of the derivative for compressible flows?
I am working on Large Eddy Simulation (LES) for compressible flows and using the Smagorinsky model to compute the turbulent viscosity $\nu_t$. In the filtered Navier-Stokes equations for compressible ...
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5answers
281views
Does the fact that the general theory of relativity predicts singularities imply that it's wrong?
Since the general theory of relativity predicts the existence of singularities in spacetime and (I think) singularities do not physically exist, does that mean that GR is wrong under that aspect and ...
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3answers
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What is the fastest possible speed of walking?
Consider a human with 2 thin legs each with mass $m$ and length $L$, and the rest of the body has mass $M$. I want to know what is the fastest speed it may walk, without leaving the ground. If we ...
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2answers
102views
How realistic is the common boat on a lake/a river problem?
The concept here is the relative motion in Newtonian physics. A boat can travel at a maximum speed of $5 \frac{m}{s}$ in still lake. The boat enters a river. The water in the river travels on its own ...
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83views
Computational power of string theory
Many years ago, I vaguely remember reading or hearing a claim that, like Ptolemy's epicycles, string theory is actually a general computing paradigm which can be "tuned" as needed to ...
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1answer
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Clarification for understanding matter fundamentally
I am entering my undergrad second year (so I have no formal quantum physics education) and have been stuck on conceptualizing matter at its core on a day to day basis. I've always envisioned matter as ...
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1answer
92views
Breakdown of the Fermi gas model for the nucleus
One of the predictions of the Fermi gas model for the nucleus is that the most energetically favorable situation for a nucleus is to have $N=Z$, an equal number of protons and neutrons. Observing the ...
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Finite Difference Modeling of MOSFET Device
Does anyone know of any references for MOSFET modeling done using the Finite Difference Method that they could point me to? I understand the gist of the operation, namely using Poisson's equation to ...
- 133
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37views
Burger equation and shock waves
Given the burger equation, $$m_{\tau} + mm_x = 0,$$ one expects to have discontinuities and thus shock waves in the case the initial conditions are smooth. For example, one may take $$m_0(x) = \sin(x),...
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