The estimation tag has no wiki summary.
16
votes
2answers
742 views
Why can't Humans run any faster?
If you wanted to at least semi-realistically model the key components of Human running, what are the factors that determine the top running speed of an individual? The primary things to consider would ...
-2
votes
5answers
277 views
Estimate number of hairs on human head [closed]
What is the number of hairs on your head? Please derive mathematically. Also show the basic assumptions if any and elaborate the procedure.
-1
votes
1answer
58 views
Rough Estimations and Approximations
As we all know, physics is a science of estimation and approximation. For example, if one were to see a tree a distance away, one should be able to estimate its height without any empirical evidence. ...
2
votes
1answer
87 views
Why do some liquid metals have anomalously-high surface tension/heat of vaporization ratios?
In a didactic article, Victor Weisskopf estimated the size of molecules in a liquid from measurements of their surface tension and heat of vaporization. If atoms are exceedingly small, then only a ...
0
votes
2answers
79 views
When do I apply Significant figures in physics calculations?
I'm a little confused as to when to use significant figures for my physics class. For example, I'm asked to find the average speed of a race car that travels around a circular track with a radius of ...
8
votes
5answers
130 views
What are the chances that a deadly asteroid will hit Earth in the next decade?
What are the chances that an asteroid that will kill multiple people will hit Earth in the next decade?
13
votes
3answers
2k views
Roughly how many atoms thick is the layer of graphite left by a pencil writing on paper?
Actually I can't expand much as the question pretty much explains the query. I would be interested in the method of estimating an answer as well as a potential way to measure it experimentally. ...
7
votes
3answers
491 views
How can we make an order-of-magnitude estimate of the strength of Earth's magnetic field?
The source of Earth's magnetic field is a dynamo driven by convection current in the molten core. Using some basic physics principles (Maxwell's equations, fluid mechanics equations), properties of ...
2
votes
0answers
53 views
Are there any connections between James–Stein estimator and quantum mechanics?
Very nice statement from wiki:
When three or more unrelated parameters are measured, their total MSE can be reduced by using a combined estimator such as the James–Stein estimator; whereas when ...
0
votes
2answers
36 views
How can I estimate the power between the guide and the sky diver?
I would like to estimate the Maximum power/ tension that can be, between the sky diving guider and the "tourist".
In this picture what the max tenstion will be, I think it is maximum when the ...
5
votes
1answer
495 views
Why do mirages only appear on hot days?
A previous question asked why the road sometimes appears wet on hot days.
The reason is that when there's a temperature gradient in the air, it causes a gradient in the index of refraction, causing ...
2
votes
1answer
123 views
How much lead is there in the universe?
I know there is around 10^80 atoms in the observable universe, but is there any estimate the amount of lead in the universe (within a couple magnitudes of 10)?
2
votes
3answers
375 views
How much energy does a super nova generate?
For a scene in a SciFi book, I want to know: Is it possible to estimate how much energy per m² an object would receive that hides behind an in-system planet when the sun goes nova?
20
votes
6answers
2k views
How fast a (relatively) small black hole will consume the Earth?
This question appeared quite a time ago and was inspired, of course, by all the fuss around "LHC will destroy the Earth".
Consider a small black hole, that is somehow got inside the Earth. Under ...
3
votes
1answer
79 views
What is an approximation of the average number of supernovae every century in the Milky Way?
Besides giving out a number and quoted source I would appreciate a short derivation of this number/formula based on our current data and knowledge of supernovae and the Milky Way. Show some traceable ...
4
votes
1answer
222 views
How to estimate condensation from air?
How to estimate the amount of water condensing from air on a surface, given the air's temperature and relative humidity and how they change over time, the surface temperature, material's thermal ...
