What is Expansion: Definition and 1000 Discussions

Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. Substances which contract with increasing temperature are unusual, and only occur within limited temperature ranges (see examples below). The relative expansion (also called strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As energy in particles increases, they start moving faster and faster weakening the intermolecular forces between them, therefore expanding the substance.

View More On Wikipedia.org
Recent contents Top users
  1. A

    I Expansion of space & expansion of matter within space

    Space evidently is expanding, so we say that the very fabric of space time is expanding uniformly in all directions, so two questions 1)originally this expansion was driven by the energy content within the universe aka the dense hot matter , versus nowdays the acceleration is picking up speed...
  2. P

    B Expansion Rate of the Universe

    I hope that I am conveying what I see in my head clearly. I guess that I am visually imagining the 3 spatial dimensions projected on the 2d surface of a sphere and as that sphere expands that the increased distance between 2 points would happen what seems like at an accelerating rate because of...
  3. C

    B Irreversible expansion of gas against gas

    Let's say I have a liter of gas at pressure of 4 atm and T=900K. I use it to move perfect massless frictionless and insulative piston to compress a liter of 1 atm, T=300K gas. When the pressure on both sides is equal and the piston stops moving, will the temperature on both sides of the piston...
  4. M

    Thermal coefficient of expansion for glycerin

    I am trying to find out where to get the Thermal coefficient of expansion for glycerin. The only thing I keep getting when using Google is mathematical examples that use glycerin as an example and its coefficient but I need to know where this number is coming from. Ex: 4.85 × 10^-4 (°C)-1
  5. EEristavi

    Thermal Expansion of a Liquid

    ##\Delta V = \beta V \Delta T####\rho _2 = \frac m {V + \Delta V} = \frac { \rho V} {V(1+\beta \Delta T)} = \frac \rho {1+\beta \Delta T}## ##\Delta \rho = \rho _2 - \rho = \frac \rho {1+\beta \Delta T} - \rho = \rho (\frac 1 {1+\beta \Delta T} - 1) = \rho \frac {-\beta \Delta T} {1+\beta \Delta...
  6. Diracobama2181

    Virial Expansion Approximation of of Lennard Jones Potential

    I get $$B_2(T)=2\pi N\int_{0}^{\infty} (1-e^{-\beta E_0((\frac{r_0}{r})^{12}-2(\frac{r_0}{r})^6)})r^2dr$$ as the coefficient. I was just unsure how to evaluate it numerically from here. Any suggestions would be appreciated. Thank you.
  7. Ranku

    I CMBR and the expansion history of the Universe

    Does the CMBR contain the imprint of the entire expansion history of the universe or only of the last scattering ?
  8. L

    Using a Taylor expansion to prove equality

    Homework Statement: Use Taylor expansion to show that for ##u \in C^4([0,1]) ## $$ max |\partial^+\partial^-u(x) - u''(x)| = \mathcal{O}(h^2)$$ For ##x \in [0,1]## and where the second order derivative ##u''## can be approximated by the central difference operator defined by...
  9. D

    Help with this formula for the Thermal Expansion of a pipe please

    I do not understand how this formula is derived: Can somebody help me? Source: https://www.corzan.com/en-us/piping-systems/specification/thermal-expansion
  10. R

    B Universe expansion rate in m/s^2 ?

    Summary: Is it possible to tell the current average universe expansion rate i.e. acceleration of expansion in m/s^2 ? Is it possible to tell the current average universe expansion rate i.e. acceleration of expansion in m/s^2 ? If i say in relation to earth, does this make it easier to answer...
  11. B

    Chemistry Computation of Liquid/Vapor Result during a Volume Expansion

    I am searching for the appropriate methodology/equation(s) to step beyond Boyle's Law to account for the phase change and solve this problem. All suggestions/guidance is greatly appreciated! Bruce
  12. Ignitia

    Chemistry Calculate the Enthropy Change of Isothermal Expansion of a Non-Ideal Gas

    Part (a) ΔS = ∫ (dq/T) because: dq = PdV = (nRT/V)dV Then: ΔS = ∫ (1/T)*(nRT/V)dV ΔS = nR ∫(1/V) dV ΔS =nR[ln(V2/V1)] Part (b) This is where I'm stuck. I know [P + a/(v/n)2][v/n - b] = RT can be solved for P and simplified to P = [RT/(v-b)]-[a/v2] since n=1mol But I don't know how to proceed...
  13. CrosisBH

    I How is a binomial expansion done?

    Summary: Can someone give me a basic high level overview on how to do a binomial expansion? I'm studying for my E&M test and going over multipole expansion. I'm particularly confused about these lines (Griffiths E&M 4th Edition) 𝓇^2_{\pm} = r^2 \left(1\mp \frac{d}{r} \cos\theta +...
  14. B

    MHB Please help for binomial expansion (2x-1/(2x^2))^9

    As titled, been cracking my head over it. Thanks in advance!
  15. pallab

    Multipole expansion for the case r'>>r and r>>r'

    for the case, r>>r' the higher-order term like 1/r^2 and above that is negligible. so V(r)=cons.*1/r*P0(cos a) but for the case r'>>r will it be V(r)=cons.*1/r'[ summation Pn(cos a')t'^n] where t'=r/r' now if we neglect higher-order term of r/r' then V(r)=cons.*1/r'*P0(cos a') which is...
  16. K

    Relativistic hydrodynamics: gradient expansion

    Hi everyone, I'm interested in relativistic anisotropic hydrodynamics and often a "gradient Expansion" is mentioned in articles, but not how this works exactly. I gathered that this is some kind of expansion of the energy-momentum tensor. Can someone explain to me how this expansion is set up...
  17. P

    I Is the backward extrapolation of the expansion of the Universe valid?

    Summary: The universe is expanding, so at one point in the past it must have been all concentrated into a single point. But is this really an accurate observation? Hi, This is my second probably naive question that's been on my mind as a lay-scientist for a long time (the other will hopefully...
  18. K

    Thermal Expansion in Liquids and Steel

    This is a repost as I didn't read the community guidelines the first time. Hopefully this is better! First thing I did was write down both the linear and volume expansion formulas. I then multiplied my alpha by 3 and used the volume expansion equation for both materials. ∆V oil > ∆V pot, at the...
  19. K

    Thermal Expansion (liquid and solid) Question Help

    Summary: Help with volume and length expansion question Hi, I am struggling with this question. I understand that beta = 3 alpha so you use this to sub into the volume expansion equation. Is this correct? Can someone please provide a step by step instruction on how to do this question? Thank you !
  20. H

    B Which rate of Universe expansion are we currently using?

    The rates I've come across are 67, 71 and 74. Obviously it's not 74 as it was just announced. Is it one of these other numbers, something else? I'm only asking out of curiosity.
  21. E

    B Distance traveled by light accounting for expansion

    Suppose light travels during a time interval of t2 - t1, where the scale factors at t1 and t2 are a(t1) and a(t2) respectively. If we consider an infinitesimally small interval of time dt during this interval, without accounting for expansion we would expect light to travel a distance cdt. How...
  22. C

    B Universe rate of expansion: speeding up or slowing down?

    A basic question... The further a galaxy is from ours, the more redshift, the faster it is moving away from us. This is taken as a sign the universe is expanding at ever increasing rate. Yet... As we look farther out into space, we are also looking back in time. If the farther we look back in...
  23. H

    B Rate of the expansion of the Universe and the Big Bang

    Disclaimer: I am parroting the information in this from articles that I've read. This post is to try to get a better understanding of what they are talking about and if any of it is relevant. I came across an article regarding the Big Bang while looking into the current rate of universe...
  24. J

    Tank Venting vs Expansion Cooling

    In the process of developing a tank venting program and starting to investigate how to incorporate tank gas expansion cooling I realized that since: T=P/nR with R constant and the reduction of P and n directly proportional then this equation implies all tank ventings are isothermal. What am I...
  25. S

    B Is the Instantaneous Expansion of Space-Time Possible?

    Given that the expansion takes place "in nothing". Given that all space-time exists all of the time. (past/present/future) If the ultimate fate of the Universe is that it collapses back in upon itself. Shouldn't a singularity of space-time occur instantaneously? After all, all time existed...
  26. Cathr

    I On Hubble's constant, the expansion of the Universe and vacuum energy

    Recently I was thinking about the Hubble's constant (which, actually, is not Hubble's and not constant...) and wondering: if the universe is expanding at 70 km/s each Mpc, then there's possible to calculate some expansion of space, say from me to a person 1 meter away from me (theoretically)...
  27. snatchingthepi

    Help with a series expansion in Marion & Thornton

    So I'm on page 67 of Marion/Thornton's "Classical Dynamics of Particles and Systems" and I'm in need of some help. I understand that so far there's is an equation that cannot be solved analytically (regarding motion due to the air resistance and finding the range of the an object shot from a...
  28. CricK0es

    Expanding a function for large E using the Taylor Expansion technique

    I have been playing around with Taylor expansion to see if I can get anything out but nothing is jumping out at me. So any hints, suggestions and preferably explanations would be greatly appreciated as I’ve spent so so long messing around with it and I need to move on... But as always, thank you
  29. C

    I Differences between the PCA function and Karhunen-Loève expansion

    Hello everyone. I am currently using the pca function from MATLAB on a gaussian process. Matlab's pca offers three results. Coeff, Score and Latent. Latent are the eigenvalues of the covariance matrix, Coeff are the eigenvectors of said matrix and Score are the representation of the original...
  30. M

    B Questions regarding expansion, the vacuum in space, and black holes

    Summary: Expansion of matter in the visible universe, total volume of space outside the visible universe, black hole mechanics, and general questions from an uneducated but extremely interested evolved monkey. Hello everyone! I do not know the rules of this forum, or any forum for that matter...
  31. saadhusayn

    Perturbation expansion with path integrals

    I expanded the exponential with the derivative to get: ## Z = \Bigg(1 + \frac{1}{2} \frac{\partial}{\partial x_{i}} A^{-1}_{ij} \frac{\partial}{\partial x_{j}} + \frac{1}{4} \frac{\partial}{\partial x_{i}} A^{-1}_{ij} \frac{\partial}{\partial x_{j}} \frac{\partial}{\partial x_{k}} A^{-1}_{kl}...
  32. H

    I Any direct measure of Universe expansion via galaxy subtended angles?

    As indicated in the title and summary, I'm wondering if there is any large scale astronomical effort to assess directly the universal spatial expansion assumed by the Doppler interpretation of the redshift/distance relationship, by measuring individual galaxy subtended angles over time. The...
  33. silverfury

    Is There a Trick to Simplify Taylor Series Expansion?

    I tried diffrentiating upto certain higher orders but didn’t find any way.. is there a trick or a transformation involved to make this task less hectic? Pls help
  34. DuckAmuck

    I Universe Expansion: Does Speed of Motion Matter?

    So the universe is expanding, and galaxies are getting farther apart from one another on average. Does this motion count the same as ordinary motion, in that if a galaxy is being expanded away from us at 0.5c, that clocks in that galaxy would appear to tick slower at 0.866 the rate of clocks here?
  35. J

    How can I expand this expression in powers of 1/c²?

    As I said before, I really have no idea on how to proceed.
  36. J

    I How Do You Calculate Initial Pressure and Final Volume in Adiabatic Expansion?

    I have a compressed pure gas at a specific temperature and volume. (T1, V1) It suddenly (adiabatically) expands until it's at ambient pressure and a specific temperature. (P2, T2). Given: T1, V1, T2, and P2, I want to find P1 and V2. There's a great example in wikipedia which is almost...
  37. G

    B Expansion or contraction -- how do we know which?

    Space/time is relative. What is the expansion relative to? Is there a reference point of no expansion to make a comparison? Accelerated contraction would appear to be expansion by an observer looking back in time so how can we be certain that the universe is expanding instead of collapsing at...
  38. Physics lover

    A limit problem without the use of a Taylor series expansion

    I tried substituting x=cos2theta but it was of no use.I thought many ways but i could not make 0/0 form.So please help.
  39. santimirandarp

    Isothermal expansion of a gas: heat of surroundings

    In an isothermal process, for an expanding gas ##\Delta U_{sys}=0## and ##Q=-W## but then, How can we evaluate ##Q_{surr} ##? It should be ##Q_{surr}=-Q_{sys}##, but I don't know how to show it in equations. If I try to get the result through the principles: ##\Delta U_{sys}=-\Delta U...
  40. M

    I What happens to spacetime during the expansion of the Universe?

    What happens to the fabric of spacetime during the expansion of the universe? Does it stretch or expand? If it does not stretch or expand, does new spacetime form to "fill the gap" as such? Hypethotically speaking, I have two celestial objects separated by a gap 1 mile wide. Due to the...
  41. Y

    I How does the expansion of the Universe affect black holes?

    I realize that my understanding of this matter and it's vast number of related concepts is rudimentary and incomplete. Kindly forgive my ignorance and try to explain your thoughts in layman's terms. Thank you for your time.
  42. Y

    I What will eventually happen to all EM waves / photons?

    I'm not an expert in this matter, and at best only aware of some superficial facts and a layman's understanding of them. So please forgive me for any ignorant mistakes in my thoughts, and kindly point them out to me. Going by the Lambda-CDM model, the expansion of the Universe will eventually...
  43. DavidCummings

    I Does the newly measured expansion rate change the odds for Big Rip?

    Is the likelihood (or unlikelihood) of a Big Rip changed by the new findings of faster universe expansion (https://www.sciencedaily.com/releases/2019/04/190425104128.htm). In https://www.physicsforums.com/threads/will-the-big-rip-basically-be-the-big-bang-for-the-next-universe.971039/, phinds...
  44. Philip Koeck

    Can the isothermal expansion of an ideal gas be irreversible?

    For the reversible expansion of an ideal gas the heat flowing out of the surroundings and into the system is equal to the work done by the system. Since both system and surroundings have the same constant temperature the entropy increase of the system is equal to the entropy decrease of the...
  45. A

    I Retaining Linear Terms of v and δ in Expansion Calculations

    While doing some calculations I came across some terms which are ##\frac{(v•\vec \nabla)v}{a(t)}## and ##\vec \nabla•[\rho(1+\delta)v]## where all quantities have spatial dependence other than "a" which has only time dependence , the first term here is canceled and the the second term is...
  46. O

    I Universe expansion discrepancy vs accelerated expansion

    Hi! Obviously my understanding is at a pretty elementary level, but nevertheless I'm puzzled by the reaction of astronomers and astrophysicists to the discrepancy in the measurements of the expansion of the early universe based on the Cosmic Microwave Background, and the measurements of its...
  47. K

    Calculating Linear Expansion with Specific Heat Capacity and Mass Density?

    Above is my attempt at a solution, however, this did not yield the correct answer. Any help is greatly appreciated!
  48. A

    I No problem, happy to help! Good luck with your studies.

    Hi, I'm currently working through a tensor product example for a two qubit system. For the expression: $$ \rho_A = \sum_{J=0}^{1}\langle J | \Psi \rangle \langle \Psi | J \rangle $$ Which has been defined as from going to a global state to a local state. Here $$ |\Psi \rangle = |\Psi^+...
  49. R

    I'm having difficulty expressing a binomial expansion as a sum

    I found the first 4 terms of the series: ½-(1/16)x^2+(1/64)x^4-(7/1536)x^6. I cannot however simplify this to a sum. the 7 in the numerator of the last term of the above expansion is the sticking point.
  50. M

    B Could accelerating expansion be caused by a "spinning" universe?

    The subject of the thread summarizes my question: Could the accelerating expansion be explained by a "spinning" universe?
Back
Top