# Questions tagged [estimation]

A rough calculation or an approximation of the value, number, quantity, or extent of something so that it is usable for some purpose even if the input data may be incomplete or uncertain.

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### How could we estimate the number of molecules below which a fluid cannot be adequately modeled by the Navier-Stokes equations?

As is known, the Navier-Stokes equations are an approximation in the continuum mechanics to model an aggregate of independent molecules, which, although they can move freely, interact strongly with ...
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### Could we be sucked up entirely by a micro black hole?

The hot question about being ripped apart in a black hole (no one can deny physics is boring!) got me thinking. If you cross the event horizon of a supermassive bkack hole, nothing noticeable will ...
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### Can a balloon start from Earth and fly to the Moon, using Helium for lift to the top of the atmosphere and then as propellant?

The JP Aerospace's Tandem airship achieved a record-breaking 28,982 meters for the highest airship flight. After reaching this height, can the helium balloon be used as a propellant, the same way if ...
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### Is there a way to calculate the blast radius of an explosion starting with the yield of the bomb? [closed]

I am working on a video game with missile-oriented combat, and I would like to input a yield for a missile instead of directly giving it a blast radius, and have the program calculate the blast radius ...
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### What is the largest hollow structure that could be made before gravity becomes a problem?

Assume realistic strength of materials, like that of steel or stone, or even something with "good" properties like carbon fiber, or advanced ceramics. If one was to put together a hollow ...
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### Taking into account the Pauli Exclusion Principle, how many particles can you cram into a really small space?

I'm trying to understand the basic concept of the Pauli Exclusion Principle, but my former question here did not provide an answer. So let me rephrase it. One way of describing the PEP is that you ...
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### Translating Parameter Estimation Principles of Quantum Weak Measurement to a Classical Problem

I am not an expert in quantum theory. I want to carry out some parameter estimation on a set of data I have. I have a model for the data with the parameter(s) of interest as variable(s). The data ...
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### What is the displacement amplitude of a 140 db sound wave?

I am teaching a unit on sound in my upper elementary science class, and my students are curious about how far air molecules are actually being displaced in a sound wave. I told them that if the air ...
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### Could a 100 solar mass black hole at 0.01c passing just at 123 AU change the direction the sun is moving by 90°?

I asked the person claiming to have created this video of such an encounter why this simulation suggests that the sun is moving in a direction that is parallel to the plane of the ecliptic? I'd ...
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### What is the terminal velocity of coin

Very little work has been done at my office for the past few weeks, as we've been bogged down in a debate on the terminal velocity of a coin (the coin in question is a local one, of 9.2g, 28.5mm ...
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### Is there a way to estimate the force of this impact?

https://www.youtube.com/watch?v=UKuPuRRNa5Q&ab_channel=BigCatPublicSafetyAct Let's assume that the tiger weighs 500 lbs, is there a way to estimate the force absorbed by its shoulders when it hit ...
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### Are there tidal forces between the solar system and the galactic centre?

Tidal forces are experienced within a system moving in free fall around a bigger object because of the different strength of gravity over the system. The difference can be calculated between the far ...
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### How deep is a gravity well of a supermassive black hole? [closed]

Just for the sake of curiosity I am trying to understand how far we should stay away from the black hole to avoid influence of its gravity on us. In the first iteration I know about the 2nd and the ...
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### Necessary mass and speed of asteroid required to make Venus spin

Suppose we are going to push a large asteroid (or two) from the belt and use them to make Venus rotate at approximately the same rotational speed as earth. Here are some questions regarding that: If ...
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### Which is more: Energy released by nuclear fission or fusion? [closed]

The energy released by one fission reaction is 190MeV and the energy released by one fusion reaction is 24.7MeV. Then by my common sense 190>24.7 so energy released by fission>fusion but the ...
1 vote
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### Is capillary pressure significant?

I have a hydraulic system pressure to be measured in cm of water. It is done by tapping a graded tube, and simply measuring the height of the water column (usually at around 10-20 cm of water). If I ...
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### How large are the fictitious forces due to our orbit around the galactic center?

When we are in a non-intertial system, this creates fictitious forces. Some well-known fictitious forces are the centrifugal and coriolis forces. Those are caused by the Earth's spin around its axis. ...
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### How was Enrico Fermi able to predict a power output from his uranium and graphite Chicago Pile 1 (CP-1) reactor?

Uranium and graphite heat engine physics - early detection methods I've been inspired by the early developments in fission heat engines which happened even before uranium enrichment methods were ...
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### Could I use magnets to lift or move something from a distance

Would it be possible to use magnets to cause some object to lift off the ground from a meter or two away? Let's assume that material cost is of no concern. What sort of object are you hoping to lift? ...
1 vote
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### Could gravitational waves be cosmologicaly 'redshifted'? [duplicate]

Is it posible that gravitational waves detected here on Earth could be cosmologicaly 'redshifted'? So, at emission they had higher frequency then after reaching Earth?
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### Are the rest frames of particles in LHC detectors approximately inertial?

Years ago as an undergraduate, I studied new-physics contributions to the reaction $cb \rightarrow tb$ in the case that the $t$ subsequently decays as $t\rightarrow be^+\nu_e$. I considered the ...
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### Considering General Relativity, how long would it take for a ball to stop oscillating dropped through the center of the Earth?

In Newtonian view, if a relatively small mass was dropped through a frictionless tunnel without drag intersecting the center of a non-rotating, spherically symmetric,uniform density Earth, then the ...
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### Is CMB slowing down all moving objects in the universe?

1/ Object moving relative to the CMB frame of reference will see the CMB blue shifted where it is heading and red shifted where it came from. Correct? 2/ The blue photons ahead should have more ...
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### How many pixels could an image of Proxima b taken by James Webb have?

I know it's very difficult for the James Webb to image Proxima b without a coronograph (I have been told by NASA scientists that they don't know yet whether they will be able to do so), but I wonder ...
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### What volume would the mass of Earth occupy in the core of the sun?

I was just wondering if anyone had computed this. I read that the pressure in the Sun's core is 3.84 trillion psi. Obviously the mass of an Earth-sized object in the core would be millions of times ...
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### Can Heisenberg's uncertainty principle be used to prove the electron can't exist in the nucleus in this way?

This is the solution given in the textbook (my analysis below it): From my understanding, I believe this solution is wrong. My understanding is that the more accurately we know the position, the less ...
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### Can weak measurement principles of Quantum mechanics be used in similar questions in classical estimation problems?

This is a surface level question and I don't want to go into detail. Imagine an algorithm which when used with a sensor output gives the statistical moments of a variable in nature (for example mean ...
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### The effect of gravitational lensing during the lunar eclipse

During the lunar eclipse, the Moon turns into bloody colour while the shadow of the Earth is casting over the lunar surface. The red hue can be explained by means of the refraction of light and ...
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### With how much energy can a charged black hole launch a electron away with?

Lets say with have a black hole with a strong negative charge, then a say a neutron falls towards it. Just before the neutron reaches the black hole's event horizon it undergoes beta decay, this ...
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### How fast can manned spacecraft slingshot from Black Holes?

I've read of Black Holes launching particles at over 99% the speed of light. Could manned spacecraft use Black Holes to slingshot ourselves at this speed, or would the G forces kill us? Intuitively, I ...
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### Would light sails be a practical means of travel in the center of Andromeda? [closed]

I've read that at Andromeda's center, stars are only 0.008 lightyears apart from each other. Is this a short enough distance for light sails to be a practical means of space travel, or is this still ...
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### Why didn't I experience violet shift at traffic signals?

context: we were studying sound waves and our instructor informed us about doppler effect and violet shift of light. Now I have many times exceeded the speed limit at night where there were no cameras ...