1:07 AM
3

The out-of-control part of the Chinese rocket Long March 5B is expected to re-enter the atmosphere of the earth and crash on the earth in a few hours. (Today is May 8th, 2021) At the moment, it is revolving around the earth in an elliptical orbit and completes a revolution in 90 minutes. Since Ap...

4 hours later…
4:59 AM
3

In the chart above, you can see the force (N) on the y axis and the horizontal position (m) on the x axis. How would you visualize this in your head? I'm trying to imagine the movement of a 1 kg box, but I just can't. Does anyone have any method or tips on visualizing the movement of a box follo...

7 hours later…
12:17 PM
1

This question got an off-topic slap on the Sci-Fi Stack because I asked about real-world physics, rather than fictional physics. I want to completely disregard the canon. Hypothetically put this into a real-world scenario where someone has somehow fit a nuclear reactor into a hilt and made a ligh...

1 hour later…
1:35 PM
2

Carroll & Ostlie's Introduction to Modern Astronomy and Astrophysics provides a derivation on why light and information is frozen at the event horizon: However I noticed that they equated $ds=0$ for light at the event horizon. But we know that the Schwarzschild metric is undefined at the event h...

2

I'm having some problem in getting an insight on what 'saturation with vapor' actually means. The question is asked in the context of atmospheric air becoming saturated with water vapor and beginning to condense. As far as I understand, when vapor is added to a volume of air, water molecules repl...

3 hours later…
4:09 PM
2

Shouldn't pressure decrease when no of moles of the substance is reduced from the system ? Since, the no of molecules hitting the surface of the system is now less ?

5:01 PM
2

Let me take you through the logic in my head... In frame S, you have coordinate $x$ Transform to frame S' with velocity $v$ so the coordinate is now $x' = \gamma x$ Now treat the S' frame as if you started there. Transform to a frame S'' moving at velocity $-v$. The coordinate is now \$x'' = \gam...

1 hour later…
6:18 PM
3

I am used to the Hamiltonian formalism in the context of (quantum) field theory, where as far as I can remember it always has the form of a kinetic term + a potential term. For me the absence of kinetic terms means a theory without dynamics. In Wikipedia the Hamiltonian of the Ising Model reads: ...

1 hour later…
7:35 PM
2

As per the title. Not that the title fact poses me big troubles, but is at least remarkable that the two assertions coexist within the same article, interview, and thread — or can be individually found on sources with reputation. What I grasp is that both are true and it is matter of point of vie...

8:01 PM
1

Why, the faster I ride my motorcycle, it gets colder and colder - while the rocket entering the atmosphere very quickly, starts to burn?

3 hours later…
11:27 PM
2

Say we hold a rope in our hand at arms length. If we move our arm towards our body slowly the whole rope moves such that there is no bending and it moves as if a straight rod. But if we move the same rope towards us quickly the lowermost part remains where it is for a split second and then begins...

11:53 PM
2

So this question has been bothering me for several days now. I've seen many YouTube videos on how "Gravity is not a Force", but no one seems to offer a simple explanation on how does this "accelerating up" thing works for the entire planet. A person sitting in India is accelerating up and so is s...