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Questions tagged [estimation]

The tag has no usage guidance.

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1answer
28 views

What are typical atomic densities of solids and gases? [on hold]

What are average values for the number of atoms per cubic cm for typical solids and gasses at atmospheric pressure?
0
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0answers
47 views

How fast can we get to Alpha Centauri?

Suppose in the near future we send an Antimatter rocket that is capable of constant $1g$ acceleration to our nearest star, Alpha Centauri, $4.3$ light years away and suppose we want the spacecraft to ...
5
votes
7answers
3k views

If the mass of the Earth is decreasing by sending debris in space, does its angular momentum also decrease? [duplicate]

We are sending huge amount of debris into space from earth, and also very heavy satellites and rockets, then the mass of earth must be decreasing over time. If the mass will decrease, then ...
1
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1answer
30 views

Is there a maximum quantum advantage in sensing?

This is a rather conceptual question. Quantum sensing takes advantage of entanglement (and other quantum properties such as squeezing) to get variances that scale much better than the ones one can ...
1
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1answer
52 views

How thick would the atmosphere have to be to block all the sunlight?

this is a question I haven't been able to find an answer to anywhere. How thick would our atmosphere have to be for the surface of the planet to be completely dark? Is that even possible? Thank you!
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0answers
43 views

How fast would a machine have to throw a basketball in Argentina to make a score in Canada? [closed]

Giving that: a. The distance between Argentina and Canada is 11,252 km b. The official weight of a basketball is 20 ounces c. There's no air or wind or any kind d. The basketball is made of such a ...
-1
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1answer
34 views

Energy consumption [closed]

If the yearly worldwide energy consumption is 80,000 TWh, and a particular earthquake generates 1.6x10^13 Joules of energy. If we could harness all of the energy from the earthquake, for how long ...
0
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2answers
42 views

Predicting the effect of a power outage on the temperature in my fridge

I have a commercial fridge, without a freezer. It is vertical fridge with one glass door. We have medications we want to keep below 8°C. Most medication tolerate a slight T elevation without problem. ...
0
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2answers
34 views

How much energy is needed to make fire?

I'm so curious about fire. So I searched a lot in the internet. And now, I knew that fire is some kind of chain reaction and combustion energy make the other molecule hot and the other molecule makes ...
0
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1answer
51 views

Is this terminal velocity figure reasonable? [closed]

I used an online calculator to find the terminal velocity of a phone falling sideways assuming it to be an aerofoil. is the value of 7500 m/s reasonable?
0
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0answers
32 views

Adequate Power Supply for 300 Daisy-Chained LEDs [migrated]

I have 300 LEDs (ws2812b) wired in a series. They were sold as 150 LED/5 meters and rated to power at 9W/m, so 45W/5m strip. I would need 90 Watts to power my entire 300 LED strip. I have a 3-rail ...
2
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0answers
28 views

At what wind speed will a ceiling fan 10 feet above my desk move a sheet of paper? [closed]

We sell fans. An engineer asked this question. He wants to buy a fan large enough to cool without being so large it blows paperwork off his desk. Q: At what wind speed will a ceiling fan 10 feet ...
3
votes
1answer
82 views

Most of the momentum of a proton is carried by the quarks

I saw this in wiki https://en.wikipedia.org/wiki/Antiproton#Modern_experiments_and_applications "the valence quarks in the proton, and the valence antiquarks in the antiproton, tend to carry the ...
7
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5answers
4k views

Why haven't we yet tried accelerating a space station with people inside to a near light speed? [closed]

Is that something we could do if we use ion or nuclear thrusters? Wouldn't people in the station reach 0.99993 speed of light in just ...
0
votes
1answer
27 views

How big of a temperature difference is needed to power a thermoelectric generator?

I'm really curious about this and haven't been able to find a formula to calculate the types of voltages I could generate based on differences in temperature. An example of interest is The PowerPot ...
1
vote
5answers
106 views

Couldn't you use a spring to increase energy?

When I was a kid I had a BB gun and when it was cocked it would compress a spring, then when you pulled the trigger, the spring would be released and fire a BB out at high velocity. I was thinking, ...
3
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0answers
71 views

Question about a hand-waving estimation done by Landau

I was reading the book written by Landau on statistical mechanics (Statistical Physics I 3rd Ed). In §1 there is a footnote that Landau wants to illustrate how accurate a statistical average can be ...
2
votes
1answer
67 views

Which are the highest energy gamma-rays produced by humans?

We can produce energetic gamma-rays on Earth in nuclear reactions but also among the decay products of LHC particle collisions. So I was wandering which are exactly the highest energy man-made gamma-...
12
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8answers
8k views

How large would the steam explosion at Chernobyl have been?

So the second episode of the HBO series began to cover the risk of a steam explosion that led to them sending three divers into the water below the reactor to drain the tanks. This occurred after the ...
0
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1answer
58 views

Was Titan once warmed by a hot Saturn, & therefore much more Earth-like than it is today?

Is it possible that 4 billion years ago, Saturn was sufficiently hot to act as a second sun to Titan, so that conditions on Titan were then similar to those on Earth?
0
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2answers
64 views

What will happen to atmospheres of very large planets?

Our earth can hold our atmosphere whereas Mars cannot. So the atmosphere retention mass must be between the masses of Mars and Earth, but if mass is to be considered then can an iron ball having the ...
2
votes
2answers
44 views

Do faster moving projectiles make larger penetration holes? [closed]

When it comes to shooting guns, a bullet of a certain size will make a certain size hole in the paper or wood target. A $.22$ bullet makes a pea size hole regardless of if its shot out of a pistol ...
2
votes
1answer
44 views

How to calculate the gravitational binding energy of a uniform cube of length $L$ and mass $M$?

The functional form is known already (as attached). But what is the solution for this integral?
0
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1answer
49 views

Correction to Newton's law of Gravity for dark energy

Is there any correction to Newtons law of Gravity that takes into account the expansion of the universe?
-1
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1answer
56 views

How long would “artificial gravity” remain on an O'Neill cylinder without power? [closed]

An O'Neill Cylinder (as defined by O'Neill, per Wikipedia) has two cylinders which are both "5 miles (8.0 km) in diameter and 20 miles (32 km) long, connected at each end by a rod via a bearing system"...
1
vote
1answer
53 views

Given that the Moon affects tides and most of the human body is water, do tides affect people?

It is known that the Moon causes tides. Given that the human body is 60%-70% water, is there any research that shows that the tides affect humans in any tangible way? If this is not the appropriate ...
4
votes
1answer
146 views

How to get the height of a constrained, infinite elastic surface?

Suppose I have an infinite elastic sheet, constrained by several poles of height 1. The height of the surface would be 1 at the coordinates of each of the poles, and converge to 0 as the distance from ...
2
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3answers
92 views

If fuel was provided by an autonomous side ship, how much fuel would be required for a 10 metric tons rocket to reach the ISS?

The point here is that the rocket weight should never include fuel. It can take off from any departure base of your choice. The fuel provided by the side ship would then be used only to lift the ...
2
votes
1answer
89 views

What percentage of a rocket fuel is used to lift fuel itself?

I don't need an exact number, also it can be to travel to the ISS or the moon, it's not important. I just want to get an idea of how much fuel is used in a «recursive» sort of way. Edit: I am asking ...
0
votes
1answer
73 views

Estimate pendulum motion

I have a simple system: a pendulum and two sensors (RADAR which will tell the distance $dx$ and $v_x$ and a Gyroscope, the gyroscope is giving me the information about $\omega$ - angular velocity) as ...
0
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0answers
31 views

How much must the Sun's radiation be reduced to offset global warming?

About 70 % of earth is covered with clouds and the rate of atmospheric water vapor is increasing. Also the warming of the oceans will most probably cause more and deeper low pressures and increased ...
3
votes
1answer
68 views

How much energy is required to perform the Saitama's moon-jump?

I have no real knowledge of physics beyond the very basics of classic Newtonian mechanics, but as far as I understand, when a particle moves closer to the speed of light, its "relativistic mass" ...
0
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0answers
43 views

How long would it take for Earth to become desolate after being slung from orbit?

I rather enjoy watching some of the what if scenarios on YouTube, and today I had one trigger my urge to seek out some knowledge on a curiosity I have. A lot of media out there explains that the ...
9
votes
1answer
670 views

Size of electromagnet needed to replicate Earth's magnetic field

I guess the title says it all. How big of an electromagnet would you need to generate a magnetic field the same as Earth's? Like, what kind of amperes are we talking here? (Assuming a hypothetical ...
0
votes
1answer
64 views

What would happen if a single 40 million cubic yard rock were to free-fall 3,000 feet onto the land below?

What if a single rock the size of the rockfall that triggered the world's tallest tsunami were to free-fall 3,000 feet directly onto land and not into water? On the night of July 9, 1958, an ...
0
votes
1answer
17 views

Can we charge an object using cathode rays?

Can we charge an object using cathode rays and use that to charge to repel and object, which is around 500 grams or so...If yes how many coloumbs of charge will it take?
1
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0answers
23 views

Contact Force of Inflating Balloon

I am trying to roughly model the contact force an inflating balloon would apply on the skin. The idea is the balloon would be constrained between an in-extensible layer on one side, and the surface of ...
0
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2answers
81 views

Force required to propel mass in vacuum [closed]

I'm not mathematically inclined. At. All. I'm a massage therapist and mental health provider. I am, however, writing a book that takes place in space. My main character (MC) is 4'11" and weighs 95#/~...
0
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0answers
63 views

At what speed in air would a solid object turn to plasma?

Just curious, friction can heat up what ever is moving. The faster something moves the quicker it heats up. Is it possible in the perfect scenario to turn a speeding solid object to plasma through ...
1
vote
1answer
51 views

What happens with the energy released after a particles collision?

From the website of CERN: "Collisions in the LHC generate temperatures more than 100,000 times hotter than the centre of the Sun.". My question is, what happens to the energy released after the ...
2
votes
1answer
59 views

Schwarzschild Radius of the Universe Part 2 [duplicate]

There seems to be some confusion as to what I am asking, so I am editing this for clarity. I know the universe is not a black hole. But if I could take all of the matter, (seen and unseen including ...
0
votes
1answer
75 views

How much more precise would LIGO have to be?

The planets and a spinning black hole both drag their local frames and thus generate gravitational waves The amplitude should be proportional to the size of the celestial body, while the frequency of ...
0
votes
1answer
41 views

How does quantum tunneling work in a bigger mass?

im trying to figure out the probability of a 9 y/o kid going right through an object. im trying to do this with a compacted form of schrodingers equation: e^(-2*(m*v/H/2pi)*l) where l = 22,34mm, h = ...
0
votes
1answer
39 views

What fraction of events goes through a small area $dA$ a distance $r$ from a spherically symmetric point source as $r\to 0$?

I'm not sure how to use limiting principle to estimate the N fraction when r -> 0 and small area dA stays fixed $ \lim N_{r\to\infty} = \lim\delta A/(4\pi r^2)_{r\to\infty}$ = 1/2 N ? How?
-4
votes
2answers
106 views

Why do people not have gravitational attraction? [closed]

Gravitational theory says every thing that has mass attract each other. So why don't people attract each other and overlap
4
votes
2answers
44 views

How much will a hole in the wing of a bumblebee affect its flying? [closed]

let's assume the holes are round shape in the middle of both wings. if the size is 1% of the whole wing, how much will be the impact? i assume this is not linear, how much will be affected if the hole ...
19
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3answers
3k views

Would a galaxy be visible from outside, but nearby?

We all know the typical sci-fi image of a guy standing on the ship deck and able to see a full galaxy. If you somehow were able to stand a few lightyears away from a galaxy would you be able to see it ...
3
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2answers
42 views

The force of wind on baseball

Does anyone know of an equation that I would be able to use for the force of wind acting upon a baseball? I am working on the projectile motion of a baseball with air and wind resistance. I have the ...
1
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0answers
43 views

Pouring Soda At A Constant Angle And Minimizing Filltime While Accounting For $\mathrm{CO}_2$

I was pouring soda, when the act made me think of a question. If you have an unopended $2L$ bottle of soda, and you wish to fill up a generic cylindrical glass cup - if you hold the $2L$ bottle at a ...
1
vote
2answers
56 views

Can Mars have an oxygen atmosphere?

It is my understanding that, in its gaseous state, oxygen molecules move fast enough to achieve escape velocity. On Earth, we see this more clearly with helium. Regardless of what's happening on ...