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Questions tagged [estimation]

The tag has no usage guidance.

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1answer
44 views

Electric force is stronger than gravitational force yet gravitational forces holds the Sun and planets in their orbits around the Sun [on hold]

The electric force between an electron and a proton, between two electrons, or between two protons is much stronger than the gravitational force between any of these pairs of particles. Yet even ...
0
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0answers
54 views

Approximate probability of a person's wavefunction collapsing to the moon?

As a sort of introductory concept to quantum mechanics, I've heard many explain that there's a small but nonzero probability of unlikely events happening: your hand quantum tunnels through the desk, ...
7
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2answers
1k views

Dissipation of energy from a noisy refrigerator

I recently bought a new refrigerator for my kitchen. The feet are adjustable but I've been lazy. Whenever the motor runs and the feet aren't all touching the floor there is a loud buzzing noise. As ...
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0answers
51 views

What speed does ice float to the surface of water? [closed]

If I were to take a 1 cubic meter sphere of ice 1 kilometer underwater (fresh or salt water, 2 degree C at 1km to 30 degree C at surface), what speed would it travel and how long would it take to ...
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0answers
12 views

How Would I Calculate The Friction of Air Displacement?

In this video by Vsauce3 we're told that if Quicksilver ran past you, that you'd feel a shock wave of air compressed around 5.7 times it's original compression, and it would be heated to 400 C, but ...
3
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2answers
42 views

High intensity laser and neutrino pair production

Given the very small rest mass of the neutrino, visible photons have plenty energy for neutrino pair creation. What would be the probability of $\gamma \to \nu + \bar\nu$? Would the neutrinos be ...
-5
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3answers
73 views

How much electricity can a kilo of electrons produce?

I know how stupid this question sounds. I heard my grandma say something close to it in a phrase "It's a 1000€ aircondition, it's not gonna consume 200 kilos of electricity !" Made total no sence ...
2
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1answer
14 views

Can we estimate the coefficient of friction between two objects/materials?

I remember reading that it was impossible to theoretically estimate the coefficient of friction between materials even if their structure was known. The book where I've read this was The Feynman ...
0
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0answers
15 views

How can I tell the approximate weight of a body, when processed from a CCTV image?

I have looked around, and cant find a suitable answer. I have a puzzle where I have a feed of a security image, and I can see a train cart move from right to left. I have to work out whether the cart ...
6
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2answers
183 views

Would a human die from high air pressure at the bottom of the Mariana trench if it wasn't under water?

I read an article recently about gelatinous fish that live deep underwater, and if they were brought up to the surface would 'melt' due to the lower pressure not supporting their bodies. This got me ...
0
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2answers
64 views

Calculating the force on a bike chain idler sprocket

I am trying to get a rough estimate of the force on an idler sprocket in a bike chain line, in order to get bearings robust enough for the task. Assuming a chain tension of 150 pounds and an idler ...
1
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1answer
31 views

How much clamping pressure would it take to hold up the weight of a human?

I don't know anything about physics. This question comes from an argument I had with a friend. Basically my question is this: Is it possible for a human to hold themselves up only by clamping their ...
2
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2answers
26 views

Why doesn't ionized air give you a current shock?

According to Tesla coil, the air gets ionized and why doesn't ionized air give current shock to a person standing in the ionized air?
17
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2answers
7k views

Uncertainty principle for a sitting person

If a person is sitting on a chair his momentum is zero and his uncertainty in position should be infinite. But we can obviously position him at most within few chair lengths. What am I missing? Do ...
1
vote
1answer
80 views

What is the minimum time required to travel 1 light-year from Earth and turn back? [duplicate]

Suppose I have a very powerful and durable rocket that is able to reach speed of light minus $10^{-1000^{1000^{1000}}}$ in $10^{-1000^{1000^{1000}}}$ milliseconds. Very instant acceleration. I can ...
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2answers
65 views

Can shining a laser pointer on an Ice Cube melt it?

I heard in videos that if you use a laser pointer (Green if I recall) and point it on a ice cube, that it would cause it to start melting, is that true?
3
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1answer
59 views

How much does NASCAR affect the rotation of the Earth? [duplicate]

Many of us will be familiar with XKCD 162: Angular Momentum, in which someone spins counterclockwise to slow down the rotation of the earth and make the night longer. The mass of an individual human ...
0
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0answers
43 views

What acceleration would I experience due to explosive decompression?

Let's say that I am a 1kg sphere with a radius of 1cm in the center of a 3m by 3m by 3m spaceship with standard air composition inside. I am currently in the middle of the vast void of space. Then ...
1
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1answer
35 views

What would happen to a person's body if they entered a black hole? [duplicate]

One of the premises of the classic sci-fi show Farscape is that a person could travel through black holes, I'm curious as to what exactly would happen to a person body if you were to enter a black ...
2
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1answer
44 views

What does the gravitational potential of the Milky Way do to the CMB?

We sit in a gravitational potential, so there should be a blue shift on the CMB light from the potential of the Milky Way. Is this blue shift dependent on direction? Is it being subtracted from the ...
1
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2answers
70 views

How fast do nuclei need to be traveling when colliding for them to break apart? [closed]

I don't mean fission or fusion reactions with uranium or such. I mean gold or lead or even hydrogen collisions, such as in these particle colliders or outer space, wherein the nuclei seem to touch, ...
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3answers
72 views

Can average acceleration be exactly determined from discrete points separated by equal time intervals? [duplicate]

I am using the American dialect of the English language. The following definitions distinguish my question from the similar, previously asked question: https://ahdictionary.com/word/search.html?q=...
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0answers
30 views

How cold does Something need to be for String Theory to be relevant?

I’ve often read casually that in order for modern string theory and other competing quantum gravity theories to be tested absolutely enormous temperatures (or rather energy densities) are required. ...
57
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11answers
17k views

Why don't solar panels contribute to global warming?

I've been wondering this for a while but I have not yet encountered an explanation. This is from my understanding of physics, which is by no means expert, so sorry for my crude explanation: Energy ...
28
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4answers
13k views

If an apple is magnified to the size of the earth, then the atoms in the apple are approximately the size of the original apple

Quoting from the Feynman Lectures on Physics - Vol I: The atoms are 1 or $2 \times 10^{−8}\ \rm cm$ in radius. Now $10^{−8}\ \rm cm$ is called an angstrom (just as another name), so we say they are ...
2
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1answer
69 views

Can the Earth's negative charge make negatively charged objects levitate?

Since the earth's surface has a negative charge, could it repel a large highly negatively charged body? An example is an object on stilts carrying a negative charge that is heavier than air, maybe ...
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3answers
89 views

Is it possible to use force to reduce the empty space in an atom?

Atoms are mostly empty space (at least from what I've heard) so is it technically possible to shrink the space between the electrons and the nucleus of an atom?
0
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1answer
41 views

At what rate does the typical human body sink in a swimming pool? [closed]

Let's say I'm $1.8\ \rm m$, $70\ \rm kg$ with a fairly typical male body shape. I hold on to the side of an otherwise normal but very deep swimming pool, then lower myself so that the top of my head ...
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votes
1answer
49 views

Estimating the minimum hole size for leakage through a sealed membrane [duplicate]

Suppose I have a thin membrane sealed onto a flat surface along its perimeter, and there is water between the two surfaces with a certain pressure $P$. I would like to know, if I made a circular hole ...
1
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0answers
46 views

How can I calculate the impulse caused by a nuclear bomb on structures?

I want to calculate the impulse caused by a nuclear bomb on structures. Is there a function that I can use to calculate the amount of impulse acted upon by a nuclear bomb depending on its size? Also, ...
-1
votes
1answer
114 views

What would happen if gamma-ray burst from a supernova burst hit the sun? [closed]

What would happen if gamma-ray burst from a supernova burst hit the sun? Would the sun explode? Would the sun expand. Have a longer lifetime? Shorter Lifetime? Because people are nit-picky about stuff ...
31
votes
1answer
3k views

Does more light from Andromeda get scattered in the atmosphere than in the entire trip to Earth?

Fires have been burning here in Northern California. Today there was just a slight haze of smoke. The sun had a slight red hue to it. As expected the lower it got the redder it became. The blue light ...
10
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1answer
248 views

What would really happen if somebody dropped a small black hole into the Earth?

Suppose we drop a small black hole, but large enough that it accumulates mass more quickly than it radiates it, into the Earth. What happens? This question has already been asked here and here, but ...
2
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3answers
80 views

If a drop of water hits something at bullet speed, will it damage it?

I can't find this anywhere. If a drop of water hits a glass for example, at the speed of a bullet, will it damage it? Or will it just make the same as a raindrop?
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1answer
203 views

How many calories in a block of wood?

I was recently thinking about the human body and the energy we get from food. I understand we don't have the ability to properly digest certain things like stones and wood and grass, but if we did, I ...
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votes
1answer
51 views

Looking at Earth's history using a cosmic mirror [duplicate]

Assuming we have a very powerful telescope, and a huge mirror 1000 light years away from earth, is it possible to look at this mirror to see what people did on earth 2000 years ago? Is it even ...
1
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2answers
137 views

Bullet hits Earth at speed $0.99c$ [closed]

According to wikipedia, the speed of the neutrino is as close as we can get to the speed of light with an object with rest mass. As per the comments, since neutrinos come in different energies, let's ...
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2answers
50 views

What if the luminosity of Sunlight increased by 10% [closed]

If the luminosity of sunlight increased by 10%, would people be able to survive outside? Would such brightness of light be very harmful to them, for exemple as much as the Mercury Vapour Lamp without ...
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1answer
59 views

What is the force behind this punch? [closed]

I originally asked this in worldbuilding due to the context, though I suppose it's just a physics question. I was never great at physics in school but let's say there's a super human and they're ...
0
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2answers
121 views

Effectiveness of cooling oneself by a hand fan

I recently had a discussion with a friend of mine regarding the effectiveness of handheld fans. My friend argued that you would always get warmer. I’m sure that this needn’t be the case, as the system ...
1
vote
1answer
31 views

How much stress do Elephants feel due to weight?

While we humans weigh around 70 kgs , Elephants weigh around 5000 kgs. My question is :While moving or standing ,how many more times than humans does the Elephant feel the stress due to weight? Is ...
0
votes
1answer
77 views

Collision Speed at which seatbelts become ineffective [closed]

In a car, what is the speed at which if you were to crash (eyeballs-out) your deceleration would be so high that your seat belt becomes ineffective and that you would've die whether or not you ...
16
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3answers
3k views

Does the Earth's rotation affect redshift measurements?

How do you account for the spin of the earth in the mechanical sense, when measuring redshift? Does the relatively slow speed of the earth have a major change in the measurement because of distance?
0
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1answer
177 views

Why trains are not heavy? [closed]

I have seen a video on youtube where Feynman explains that engines of trains are heavy to compensate for the fact that steel has a low coefficient of friction. But, whereas this seems plausible for ...
1
vote
1answer
40 views

Whats the energy spent on a push-up? [closed]

Let a human of height 1.80 m, arm length of 0.5 m and weight 80 kg do a push up. How much energy did she spend? $$ F = m \cdot a $$ $$ E = F \cdot s $$ $$ \rightarrow E = m \cdot a \cdot s,$$ where $...
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1answer
53 views

How loud would a sound have to be for it to travel the distance of Pittsburgh, Pennsylvania to New York, NY? [closed]

I'm just wondering if it's possible, more than anything. But if it is, how many decibels would the sound have to be to travel that far of a distance?
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2answers
2k views

How far can a shout travel?

I was wondering, if a person climbs a tower and shouts at the top of his lungs how much distance would the sound travel ? Would it reach someone 1km far? Assuming that there are no tall buildings in ...
35
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1answer
9k views

Can I eat myself into a black hole?

This was a humorous thought experiment that occurred while chatting about black holes. The person that I was talking to assumed that a black hole required a specific density to be achieved. I pointed ...
6
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3answers
188 views

Dam Son's problem: how long does it take to boil an ostrich egg?

The egg boiling problem is a seemingly simple problem posted from the blog of UChicago's physicist Dam Thanh Son. A chicken's egg has a length of 5 cm and takes 6 minutes to boil. An ostrich'...
0
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1answer
102 views

How loud is the sun? [duplicate]

The sun is a continuous explosion. The reason we cannot hear the sun is because of the vacuum separating us. If that space was to be filled with air, would the sun be audible?