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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Coriolis effect in the bathroom? [duplicate]
I understand that the Coriolis effect is not responsible for the spin effect in the bathroom, but I have never seen a rigorous math prof of this. Where could I find a proof of this? What references ...
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GRB 221009A Comparison with solar flare NOOA scale
I'm trying to found a comparison of the energy received on Earth by GRB 221009A in comparison of various solar flares based on NOAA Space Weather Scales (or other).
I failed to find any comparison (...
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Can I guess the order of magnitude of the current inside a spark based on a picture?
In this video, Steve Mould explains how an inflammable gas can be ignited with a spark created by the piezoelectric effect. At 01:11, there is a close up on the spark with a scale in the background.
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How much radiation on the surface of the moon during a Coronal Mass Ejection (CME)?
I'm writing a book set on the moon. A Coronal Mass Ejection (CME) as large as the Carrington Event hits it. Three astronauts are caught out during an EVA. They will cover their rover in regolith to ...
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Does a geodesic exist that will take someone across the event horizon?
I saw the movie "Interstellar" a few years back, and was amazed that Cooper was able to fall from 1 AU into a black hole before his daughter turned 110. Intuitively, I would think that there ...
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Nuclear fission in the Sun
The Sun's energy comes primarily from fusion of light elements in its core.
It is estimated that a very small fraction of mass of the Sun (~$10^{-12}$ times the abundance of hydrogen) is uranium (both ...
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Estimation of errors in actual experiments
I encountered a statement in a research paper I read which confused me-
“In order to estimate the random error in our data, we calculated the average distance between a line of best fit and the ...
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At the TOV limit (almost black hole), how much of a neutron star's primordial mass has been converted to energy?
The following rough approximation seems to show a neutron star at its Tolman–Oppenheimer–Volkoff limit of 2.17 solar masses and 12km radius, has gravitational binding energy on the same order as its ...
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How fast must an incompressible ball, with mass $M$ and radius $R$, rotate to form a black hole?
An incompressible sphere with a uniformly distributed mass $M$ and radius $R$ is rotating in empty space. How fast must the sphere rotate to form a black hole? Will this happen when the kinetic energy ...
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Is overusing gravitational slingshots a real concern?
I was thinking of the trading of kinetic energy during a gravitational slingshot maneuver and wondered if the kinetic energy lost during that process makes any noticeable impact on the orbit of the ...
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Can a tea light really heat a greenhouse?
It is a common suggestion amongst greenhouse enthusiasts that a long-burning tea light inside an upturned terracotta pot can be enough to keep frost away from plants. Is this possible?
Instinctively, ...
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Distribution of weight for a heavy table top [closed]
I've had a table base, 36"Wx29"Lx40"H, made for a heavy marble top, 59" x 64 3/4", that weighs roughly 300lbs. Is this a proper distribution of weight for this base?
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If the oh-my-god particle hit you, would you notice?
I was reading about the 'OMG particle' and was wondering what would happen if it hit a person (before it went through the atmosphere). I did a search and most answers said you wouldn't notice. Which ...
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What is the most highly charged celestial body in the universe?
Generally speaking, the universe is electrically neutral and
the universe abhors an unbalanced charge.
Wherever there is a positively charged object, you can bet there is a negatively charged object ...
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Viewing String Oscillations with a Camera
In this video, a demonstrator shows normal modes on a string. If one is doing this with a high speed camera, how many frames per second does one need to view the oscillations?
My intuition was that ...
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Can gravity of planets besides Sun and Moon affect tides on Earth?
The tides in some places on Earth are over 50 feet. If the gravity from Venus had a ten thousandth the affect of the Sun and Moon on a 50 foot tide it would make a difference of one twentieth of an ...
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Are gravitons radiated while the massive body turned making Earth orbit unstable?
When @anna v explained why the planetary model of the atom does not make sense in this post, she said the electron in an orbit is accelerating continuously and would thus radiate away its energy and ...
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How much salinity is needed for everyone to float?
Everyone floats in Dead Sea because it is so salty. Is it true in Great Salt Lake? How about Red Sea and Mediterranean Sea? Is it impossible for anyone to sink in these seas without added weight?
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Closest possible flyby to a nonrotating supermassive black hole
Imagine you think Laplace is the last word on black holes. That is, you are aware of the radius for which the escape velocity is $c$, but you think gravity is Newtonian. You set your spacecraft on a ...
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If light had mass
Is there any way to know how fast would light be if it had a mass? Something like 0.000000178536 kg. At least a formula to help estimate it would help, i asked chatgpt and it said ''E = mc²
E = (0....
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Reduced mass vs. Total mass in gravitational wave estimations
When people do back of the envelope calculations about GW physics, they always use a very abstract mass scale $M$ and I want to figure out the identity of said scale for different relevant magnitudes ...
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Could a human-sized flea really jump over the Eiffel Tower?
I am puzzled why so many people think such a large flea could jump as high as the Eiffel Tower. We know that a 3mm long flea can jump 150mm, which is 50 times its own length. So I suppose it's ...
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Is Sun not the biggest source of energy to us?
Probably in my 5th or 6th grade, I learnt in my science classes that sun is the biggest source of energy to us.
However, I was watching this youtube video according to whom the energy of earth is ...
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How much energy is required to remove Earth from it's orbit and exit the solar system under perfect conditions?
Ok, this is my first question on this site. But it's one I've been thinking about for a while.
Say through whatever means, we place a device capable of generating thrust/ kinetic energy on the surface ...
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Air resistance in the Cavendish Experiment
Would air resistance be an issue in the Cavendish experiment or are the velocities so low as to be irrelevant? Could it cause the experiment to fail?
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How small can velcro be?
Note: "fiber" refers to individual hooks and/or loops.
Imagine two flawless graphene sheets, one with atomic diameter hydrocarbon loops attached to one face, one with atomic diameter ...
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For Two Bodies At Rest, How Many $g$'s Before General Relativity Matters?
I'm an EE, so please forgive if this question is dumb.
It is my understanding that in GR, acceleration can curve spacetime, even if the velocity between two bodies is not comparable to the speed of ...
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How many typical nuclear power plants does it take to power 1 billion typical cellphones per year? [closed]
Not asking for an exact answer clearly.
Let us say that a cellphone user typically watch like 2 hours of video per day and it is say on an iPhone of your choice.
How much power would be needed to ...
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Will a man acquire orbit if we suppose Earth is rotating fast enough?
if we consider that the rotation of earth is mush faster (30000km/h), so if a man standing on earth jumps 1 meter above will it acquire orbit if we ignore atmospheric friction
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What was the size of the observable universe at the matter-dominated era and its mass density?
For instance, at the scale factor $a=0.5$ and matter dominated era, what was the size of the observable universe and matter density?
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What is the expansion of space of one megaparsec in one year?
suppose we know Hubble's constant. In a hypothetical scenario an astronomer finds and confirms Hubble's law for a galaxy 1 mega parsec away.
Next year, how much distance will the hypothetical ...
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What would be the size of a hydrogen atom with its electron if it's scaled up?
I began wondering that if I wanted to make a precise scale model of a hydrogen atom, with the electron being $1$ cm in size, how big should the nucleus be and how far away should the electron be from ...
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How close would a evaporating primodial black hole be to be detected? [closed]
The power output of a black holes hawking radiation is inversely proportional to the square of it's mass. According to here, in it's final second of existence, it'll emit over 2E22 joules of energy, ...
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Can time in space be years faster than on Earth? [closed]
Is it possible that in some distant solar system from another galaxy, time will be dramatically different from our Earth time, with years passing far faster than on Earth time?
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What’s the lightest you could make a "star" if you made it out of different materials?
What’s the lightest you could make a "star" if you made it out of different materials?
How large would the "star" be?
For example according to here https://astronomy.stackexchange....
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What are the similarity and difference between quantum fidelity estimation and parameter estimation problem?
Quantum fidelity estimation is to estimate the similarity between two quantum states or process. Could quantum fidelity be viewd as a parameter? And what are the similarity and difference between ...
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How long does it take for gas to settle down under earth's gravity?
I was discussing about ideal gas with my colleague the other day, and these questions come up in our conversation.
Lets say we have 1 mole ideal gas in a perfectly insulating cube box of size $1m^3$,...
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Need clarification/input on a curvature dilemma
Even though I said I'd never waste this much energy arguing with a flat earther, I have a dilemma and need input.
I'm in the Vancouver, Canada area. I've been shown a picture that the person claims is ...
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How was the Titan submersible implosion time calculated?
Many experts commented about the Titan submersible that the implosion took few milliseconds. What is that assertion based on? What physics computations lead to that time?
I had imagined an abstract ...
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Energy with mass correlation
If the watch is working/ticking, its moving parts (gear, hand) contributes to extra mass where if we add potential, kinetic, and thermal energy and divide it by $c^2$, we get extra mass (small, but ...
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What are the experimental difficulties in measuring the Unruh effect?
The Unruh effect was predicted in 1976.
As someone with no background in experimental physics I find it surprising this effect hasn't been measured yet. What are the experimental difficulties (and ...
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How close to a lightning strike to be perceived at 140dBP, or to risk permanent hearing loss?
I was caught in an electric storm last night while camping. The time between flash and thunder must have been 3 seconds or less at least five times. (The nearest hill peak which could have been ...
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How can I justify the energy levels of a hydrogen atom heuristically?
In the future, I will need to teach students at school the proportionality $E_n\propto-\frac{1}{n^2}$ of the energy levels of a hydrogen atom. I could present this as an experimental fact, but I would ...
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Help me understand extreme pressure
So we have the tragedy of the submersible being lost near the Titanic site.
I am trying to understand the pressure the vessel was under. I have heard the "$1$ atmosphere for every $10$ meters&...
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Back-of-the-envelope estimate of thermodynamic cost of food absorbtion from first principles
Just out of curiosity, I'm trying to get a sense of the order-of-magnitude theoretical thermodynamic cost of food absorbtion. I'm thinking of food absorption as "move nutrients in newly consumed ...
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How fast can the human hand move?
I was playing with my six year old daughter the other day with her toy airplanes (I’m a pilot and she’s very interested in aviation now). I took the little F16 toy and flew it passed her as quickly as ...
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Largest momentum a man can generate with his body? [closed]
With just the human body and no extra help (e.g. no gunpowder), what is the maximum momentum one can impart to an object?
As an example, the fastest a human has thrown a baseball (weighing 0.145 kg) ...
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Why are departures from flat spacetime geometry small on scales smaller than the Hubble radius?
In Chapter 5 of Baumann's cosmology book where he discusses structure formation starting from Newtonian perturbation theory, Baumann mentions at the beginning that
Newtonian gravity is a good ...
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Gravity of pyramid effect on person? [duplicate]
so I recently just thought of a situation and I couldn't find an answer to why this is online.
The great pyramid of Giza has a mass of approximately 5.9 billion kilograms. I have a mass of about 75 kg....
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How do you calculate the time taken in a collision?
For example a car with a known speed and mass crashes with a completely unyielding wall. The car has a crumple zone, (and you know the modulus of the crumple zone) so it doesn't stop immediately, but ...
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