The order-of-magnitude tag has no wiki summary.
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For how long must a molecule remain stable to be considered “stable”?
In the Star Trek: Voyager episode The Omega Directive, Seven of Nine says that the Borg synthesized a molecule which was "kept [] stable for one trillionth of a nanosecond before it destabilized". ...
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Can the solar system really fit in a thimble?
Almost every time somebody talks about atoms, at some point they mention something like this:
If we remove the spaces between the atoms and atomic components, we can fit the solar system in a ...
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Why do some liquid metals have anomalously-high surface tension/heat of vaporization ratios?
In a didactic article, Victor Weisskopf estimated the size of molecules in a liquid from measurements of their surface tension and heat of vaporization. If atoms are exceedingly small, then only a ...
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Explanation of energy levels in molecules, atoms, nuclei and their relationship
Why are the energy levels of molecules, the atoms that form them and the nuclei inside the atoms considered separately? Or phrased in a different way- what is it that makes their energy levels so ...
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Forces: Worth worrying anything?
I am a general physics student, I had a question in my text-book and according to it two students having gravitational attraction between them = ($6.67\cdot10^-8\ \mathrm{Nm}^2/\mathrm{kg}^2$) is not ...
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Design of experiments to determine proportionality
A common result of theoretical analysis in physics is some sort of relation derived from physical parameters and typically expressed in the form of a non-dimensional parameter. These scale relations ...
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Planck mass is about the mass of one eyebrow hair
Unlike most Planck units named after "Planck" such as Planck length, Planck temperature, etc, the Planck mass seems more closed to daily life. It is about $10^{-5}$g, same order of magnitude of one ...
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Heuristics for specific heat capacities of solids
A didactic question publish in The Physics Teacher (http://tpt.aapt.org/resource/1/phteah/v41/i1/p8_s1) asks which will melt more ice: 100g of metal at 100C or 100g of wood at 100C. (The particular ...
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How much water is destroyed in photosynthesis, relative to the world's supply?
Water is involved in the photosynthesis. How much water are we talking about compared with the total amount on water on Earth? Is it enough to have an effect on the average age of water molecules?
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Energy behind door knocking?
How do we estimate the energy released from knocking on a wooden table or a door?
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How did Enrico Fermi calculate the classical Fermi Problem?
From Wikipedia:
Fermi was known for his ability to make good approximate calculations with little or no actual data, hence the name. One example is his estimate of the strength of the atomic bomb ...
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Modeling galactic colonization
I found a really cool sounding order-of-magnitude modeling question but am a bit at a loss on how to approach this:
The Milky Way contains 100 billion stars and has a radius of 250,000 light ...
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Why do mirages only appear on hot days?
A previous question asked why the road sometimes appears wet on hot days.
The reason is that when there's a temperature gradient in the air, it causes a gradient in the index of refraction, causing ...
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Understanding pregnancy length and life time based on dimension analysis and order of magnitude estimation [closed]
Based on dimensional analysis and order of magnitude estimation one can understand why for example no warm blooded animal of small size such as rats can live in the north pole, only big animals like ...
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Confront Order Of magnitudes
Is it correct to say that 9.0 is one order of magnitude smaller than 10.0?
Has anyone a link/source about confronting order of magnitudes, apart from wikipedia?
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How much would the LHC beam be attenuated by the atmosphere?
As I understand it, the completed Large Hadron Collider (LHC) will ultimately have a proton beam with $2,808$ bunches of $1.15 \times 10^{11}$ protons each at $7$ TeV, giving a total beam energy of ...
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773 views
A Fermi-question: Are there more stars than grains of sand?
This claim is pretty popular in the web and obviously cannot be answered by counting grains or stars. Thats what physicists call a Fermi-question. It deals with problems/questions where we dont have ...
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How cold does it need to be for spit to freeze before hitting the ground?
What is the dominant form of heat transfer between warm water and cold air?
If a $100 mg$ drop of water falls through $-40 C$ air, how quickly could it freeze?
Is it credible that in very cold ...
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Is there a number that describes a gas's departure from the ideal gas law?
When judging if relativity is important in a given phenomenon, we might examine the number $v/c$, with $v$ a typical velocity of the object. If this number is near one, relativity is important. In ...
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How does the temperature of the triple point of water depend on gravitational acceleration?
Suppose I do two experiments to find the triple point of water, one in zero-g and one on Earth. On Earth, water in the liquid or solid phase has less gravitational potential per unit mass than water ...
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Turned to steel in the great magnetic field
This is obviously a "fun" question, but I'm sure it still has valid physics in it, so bear with me.
How great of a magnetic field would you need to transmute other elements into iron/nickel, if ...
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How can we make an order-of-magnitude estimate of the strength of Earth's magnetic field?
The source of Earth's magnetic field is a dynamo driven by convection current in the molten core. Using some basic physics principles (Maxwell's equations, fluid mechanics equations), properties of ...
