# All Questions

727 views

### Carousel; explanation of a certain phenomenon.

There are countless of hilarious youtube videos like this one here, in which you can see that the carousel causes people to be pulled outwards. What force is actually working on them, and why does ...
5k views

8k views

### How air humidity affects how much time is needed for heating the air?

In cold weathers it is suggested to put a humidifier since the air gets too dry. I wonder how the humidity affects how much time is needed to get the air at a temperature of 20 Celsius degrees? I mean ...
252 views

### Representing a polarization vector for light as a 'manifold of two state'

Explain me these projections please Context: I was reading a paper (Phys. Rev. A 68, 052307) which involved mesoscopic coherent states of light. There, in order to calculate the uncertainty of a ...
2k views

### How to calculate the supporting force for a cantilever beam? [closed]

How do I find the supporting force $R_A$ and the moment $M_A$? Should I use the sum of moments or?
479 views

### What was the muzzle velocity of a home made gun launch strait in the air if air time was 8.2sec?

I built a potato gun and wanted to calculate the muzzle velocity. I remember from physics that I could run the numbers by calculating time from launch until landing. After pointing strait into the air ...
351 views

### What is the definition of density as a function?

(Before I start, I don't know which tag is suitable for this post. Please retag my post if it bothers you.) Let's say there is a string on $[0,1]$ with a mass given by $m(x)$. ($m(x)$ means the mass ...
11k views

### Why does an object with higher speed gain more (relativistic) mass? [duplicate]

Today, in my high school physics class, we had an introductory class on electromagnetism. My teacher explained at some point that an object with a very high speed (he said it started to get somewhat ...
2k views

### Fast cool down of “things” in the kitchen

Is there any fundamental physical reason (thermodynamics/entropy?) behind the fact that there doesn't exist home appliance for fast cool down of food/drinks? I know that there are some methods ...
1k views

### How can some-one independently do research in particle physics? [closed]

I'm not affiliated with a physics department and I want to do independent research. I'm working my way through Peskin et. al. QFT now. Let's say that I've finished Peskin et. al. and Weinberg QFT ...
349 views

### Exploding Earth

I have always heard that the Earth, due to its structure, cannot explode. Now, I'm quite fascinated by astronomy physics but I admit I only hold some more than basic knowledge. In any case, even ...
128 views

### Can we use a warp bubble for nuclear fusion?

I understand NASA is now experimenting with a tweaked Alcubierre drive. Apperantly some physicists predict crazy heat (hotter than the sun) inside the warp bubble caused by Hawking radiation (recent ...
58 views

### Can objects, animate or inanimate, be constructed out of basic particles?

If all the elements are made of protons, neutrons and electrons, but some elements are much rarer and more expensive than others, would it be possible to break apart atoms of one element and make ...
180 views

### Special Relativity [closed]

Could someone explain to me how special relativity works? I know there are thousands of sources and databases of knowledge out there, but I find it difficult to understand, even after reading up on ...
865 views

### How do the Einstein's differential equation of the curvature of spacetime come out of Einstein's field equation?

The classical theory of spacetime geometry that we call gravity consists of the Einstein equation, which relates the curvature of spacetime to the distribution of matter and energy in spacetime. ...