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 ...
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 ...
As a planet moves through the solar system, a bow shock is formed as the solar wind is decelerated by the magnetic field of the planet. Presumably the creation of this shock wave would cause drag on ...
In the movie Frozen, the following dialogue takes place: Anna: "It's a hundred-foot drop." Kristoff: "It's two hundred." Anna: "Okay, what if we fall?" Kristoff: "There's 20 feet of ...
The physics TA showed us a few examples in which one can estimate many things from first principles, sound logic, and scaling arguments. This led usually to understanding of why some numbers have the ...
I can calculate that if you want to, for example, desalinate water, you will have to pay a free energy cost of $k_B T$ for each ion you remove. In other words, removing an ion from a volume of water ...
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 ...
I'm doing some research on how much force is required to move a typical raindrop (assuming that it is falling straight down) off to the side of X distance. This is for a school project on creating our ...
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)?