Questions tagged [estimation]

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1answer
42 views

Is a laboratory space a (decent enough) inertial system?

regarding a 1m x 1m x 1m space (e.g. at LIGO) and a particle (e.g. a proton) moving at $0,96\cdot c$ I was wondering if this space could be treated as an inertial system. I calculated that from one ...
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3answers
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What would happen if all protons in the Sun had a charge of 1.000001 times the elementary charge?

The whole sun would be positively charge, but would it explode because of it? Or would it just expand a bit?
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Does home cooking induction stove produces any harmful (to humans) electrical/magnetic fields?

An induction cooker, or stove that are based on the principle of electromagnetic induction, and is used much, for cooking food now a days. My stove had a thick iron circular plate on the top. Assuming ...
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What amount of force does the average person exert when hammering a nail into an object/concrete? [closed]

I am designing a long reach hammer that can pile nails into concrete that's used for reinforcement and formwork for my senior design project. I just need to know how much force one exerts with a ...
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1answer
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Do Particle Accelerators Generate External Electrical or Magnetic Interference?

Among others, I am engaged in private pendulum research work during which there have been reports of disturbances of unknown pseudo-periodic human origin. It has been surmised that transmitted noise ...
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4answers
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Why do bullets shoot through water but not through sand?

There are a few questions only on this site about this but none of them answer my question. Can cannonballs go through water? Why does a bullet bounce off water? I find it hard to understand why ...
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1answer
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Distance between molecules in outer space

I read that space has a pressure of about $1.322*10^{-11}$. I am curious to know how far apart molecules are from each other because of this extremely low pressure.
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3answers
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How can you show that the Moon's gravity is one sixth of the Earth's? [closed]

I've tried using \begin{equation} F_s = \frac{GMm}{d^2} \end{equation} but I got this answer: $1.8704 \times 10^{20} $ I'm not sure what I'm doing wrong?
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1answer
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If 30dB at 200 meters away, how much at origin? [closed]

I want to organize an event in a public area, and I'm not sure how loud we can get. If the limit is 30 dB as measured at 200m away from the origin of the sound, what is the limit from its origin, in ...
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1answer
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Is galactic gravitational lensing self-magnification big enough to contribute noticeably to the galaxy rotation curve problem?

Gravitational lenses magnifies the appearance of themselves, so in the case of a galaxy it looks bigger than it is. Thus the outer stars in a galaxy seems to have a higher tangential velocity. For ...
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1answer
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Why don't we burn ourselves when we speak?

In this post we learn that sound transfers a lot more energy than heat across the medium, so why don't we burn ourselves when we speak by generating sound? Does sound reflect more easily than heat?
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4answers
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Stood in front of microwave with the door open [closed]

I was cooking something in the microwave and opened the door early to check on it and the microwave didn't stop. I didn't realize this for a few seconds and when I did I shut the microwave off but I'm ...
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1answer
102 views

How much energy per area or volume is the solar wind producing?

Would it be possible to erect essentially a giant loop of wire in interplanetary space to create an electric generator? If so, how much power can we get?
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1answer
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Calculate liters of water flowed on a pipe at a given pressure and time

I am having a really hard time getting the answer to this apparently simple question! I have a vertical pipe on my house with cross section area A and lenth L. The pipe is completely filled with water....
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1answer
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Moisture evaporation from paper

Is there a way to calculate moisture loss from a piece of paper in contact with a heat source. If you have roll of paper 1 meter wide of infinite length the paper weight is 130g paper per m2 with 8% ...
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0answers
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How many electrons per second an electron beam generator needs to produce in order to obtain 7E-8 kg of positrons with a high energy laser?

I have read that one way to produce antimatter is pair production through the use of high energy lasers. The process consists in shooting a laser into a cloud of electrons, which ...
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1answer
45 views

How much potential energy is stored in a city's elevators?

This is probably along the lines of one of those vague Google interview questions. It also assumes naively that elevators could generate energy when going down, but yeah: How much potential energy is ...
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1answer
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Energy required to tilt Earth’s axis by 90 degrees? [closed]

How much energy would be required to tilt Earth’s rotation axis in such a way that what is now poles would be where to equators are relative to Sun and vice versa?
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1answer
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How many neutrinos would it take to kill you?

Of course, there are many different kinds, so let's assume: they'rre all standard $v_e$. they all intersect your body in random places. they are going at say, 10% of c (about accelerator speed). ...
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3answers
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How much pressure will be generated if liquid helium is placed in a sealed container at room temperature? [closed]

I know that helium has the lowest boiling point so I was curious how much pressure it would exert if liquified and trapped?
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2answers
155 views

How much antimatter could a 100-Petawatt laser produce in outer space? [closed]

How much antimatter could a 100-Petawatt laser theoretically produce during (for example) 30 femtoseconds? The laser would produce electron-positron pairs using the mechanism outlined in this article ...
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5answers
96 views

Will liquid nitrogen evaporate if left in an unopened container? [closed]

SOS! I left work today and got a horrible feeling that I forgot to put the lid back on a large container of liquid nitrogen which contains many racks of frozen cells in it. If this did happen, how ...
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2answers
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Why gravitational waves are hard to detect?

I just started to learn general theory of relativity by Hartle's gravity textbook. In a section on gravitational wave I encountered following statement 'Gravitational waves are hard to detect due to ...
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What is the output pressure graph in my simple Pneumatic system?

I am doing basics Pneumatics and I have a question about how one would calculate the following. In general I hope to get an idea of how to dimension Pneumatic systems. I have done differential ...
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4answers
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Can you shake a charged object fast enough to create light?

Electromagnetic radiation (a photon) is generated by an oscillating charged particle. Therefore, is it possible to vibrate an object at say 585 THz and create a green light source? Alternatively: what'...
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1answer
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What are the major difficulties to the production of elements?

Searching online about this topic only gives results about nucleosynthesis (making elements by nature) and the 24 radioactive artificial elements. Why isn't there any information about methods to make ...
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2answers
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Can lightning be used as a source of energy? [duplicate]

Is it possible to use lightning or thunder as a source of energy, with the help of dielectric breakdown and splitting?
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2answers
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Is it safe to keep uranium ore in my house?

I bought 5.6 gr of uranium ore. The measured gamma radiation is 1µSv/h, we didn't have the instruments to measure alpha/beta radiation. EDIT: The gamma radiation was measured at 1cm distance. I also ...
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1answer
50 views

Why don't we observe quantum effects for large massive objects at rest? [duplicate]

The de Broglie wavelength of any massive particle is $\lambda = \frac{h}{p}$. We know that if a large object (say, a baseball) is at rest, it will have $p=0$ and hence $\lambda$ will be infinite. This ...
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0answers
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What's the difference in force between lifting an object out of a viscous fluid (like honey) versus air?

Roughly, how much more force does it take to lift a stick out of a viscous fluid (like honey) than the same object the same distance in air? I'm not looking for a hard number- more like a back of the ...
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1answer
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How would one estimate the age of a black hole?

The age of the universe is a question that has long been asked and supposedly been answered. My question however is a lot more specific rather than a general age of the entire universe. How would one ...
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5answers
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Could you theoretically build an nuclear-blast-proof safe? [closed]

Some bulletproof safes are sturdy enough to handle grenade impacts. Could we theoretically make an analogous atomic-proof safe that will handle something like an Hydrogen Bomb? It doesn't matter the ...
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Does it make sense to ask how many of the molecules you are inhaling Caesar exhaled in his last breath?

There is a nice example of a Fermi estimation question where you ask: How many of the molecules which Julius Caesar (or Jesus, Muhammad, etc. - anyone who died a long time ago) exhaled in their dying ...
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Real life examples comparable to number of electrons in $1\rm C$

In order to teach 7th-grade students of the enormity of the number of electrons in 1 coulomb of charge $$1\ {\rm C} =6.25 \times 10^{18}~ {\rm electrons}$$ I wish to compare this number to a real-...
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What would happen if a 10-kg cube of iron, at a temperature close to 0 kelvin, suddenly appeared in your living room?

What would be the effect of placing an object that cold in an environment that warm? Would the room just get a little colder? Would it kill everyone in the room like some kind of cold bomb? What would ...
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1answer
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Solving global warming by moving Earth closer to Mars

One way to reduce global warming is to get our planet farther away from the Sun. If we placed a couple of thousands of SpaceX's Merlin rockets upside down in the tropics or Sahara i.e. somewhere where ...
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1answer
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How tight does a piston need to be to retain water at 80 PSI and room temperature?

This question involves computing the minimal space that water will leak through. For example, if we have a piston and cylinder and the water in the cylinder is at 80 PSI, what is the maximum clearance ...
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1answer
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How to determine maximum speed for a given bicycle gear ratio?

This question came up watching a final sprint at the Vuelta San Juan this year. One of the riders was sitting down in the sprint because he had "spun out" his gears, meaning there was no ...
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1answer
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If you swing anything fast enough, can you nail a nail?

You have a nail set in a piece of wood for example. Theoretically if you swung something else at it, no matter what it was, could you drive the nail in, if it were moving fast enough. I get that the ...
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2answers
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Can we stop asteroids from hitting the earth using a laser? [closed]

This new video from Veritasium talks about the probabilities of an asteroid hitting the earth and the destructions it can cause. At last they talk about how can we prevent an asteroid from colliding ...
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What is the total internal energy of a liter of water? [closed]

How does one calculate the total internal energy of a liter of water? For an ideal gas, the case is simple. $E = c*n*T$, where c is the molar heat capacity, $n$ number of moles, and $T$ the ...
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1answer
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If the moon became a black hole, how much lower would the temperature be on Earth's surface?

I read that if the Sun became a black hole the Earth would become colder, but the effect would be negligible because the mass of the hole is still there so there would still be tides. But, how much ...
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1answer
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How close can we calculate back in time to the instant of the big bang? (until, presumably we need a theory of quantum gravity?)

I've heard a few times in my 5+ decades that we can only calculate the "state of the universe" (loosely speaking, I don't know any math close to that high) back to very close, but not right ...
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1answer
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Could Black Hole be formed with the center of some stars? [duplicate]

If the LHC might make black holes, why would tiny or not so tiny black holes be potentially created with the very hot and dense core of a really big star?
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Another way for production of positive fusion

I am wondering why energy positive fusion cannot be produced in the following manner. Large tank of hydrogen pressurized to such a high a level it would push the limits of current technology. ...
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1answer
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Why are extremely small masses expected to be in relativistic motion?

For example, neutrinos have an extremely small mass and are expected to be in relativistic motion. Why is that so?
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We know a human cannot run on water, but could a much stronger and faster animal?

We know a human cannot run on water, but could a much stronger and faster animal? This viral video shows a moose running across a body of water: https://www.youtube.com/watch?v=K5-0d00hV1c Some say ...
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1answer
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Can a 3500 Watt Laser fired from the Earths' surface have a measurable impact on Mars?

Recently, I came across a video on the BBC website which stated that people were 'blasting 3500 Watt lasers' at Mars. The article (https://www.bbc.com/news/av/uk-england-hampshire-54930207) goes on ...
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1answer
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Are we gaining or losing time as our planet revolves around the Sun?

I understand that the Earth (or someone standing on our planet) will undergo time dilation due to a number of reasons compared with someone hovering in interstellar space. I would like to focus on two ...
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How to calculate the Likelihood function of a gaussian pdf

Suppose a model for a flux of (astro)particles $\dot \Phi(E,t)$ (from a supernovae) that depends on particle energy $E$ and time $t$ (from beginning of explosion), and 3 free parameters $T_a, M_a, \...

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