Mystery Definition and 913 Threads

Hi , In one of my friends place , she cut the lemon in half and left it . She saw the lemon rotated to other direction by itself . She saw it twice on different days ,why does this movement occur ?

Any clue what this would be?

Hello everyone, Imagine the following situation: You are inside the events horizon of a static black hole (called BH1) Now, due to the bended space-time, your future points to be inside the event horizon until eternity (You will never be outside) Now, a second static black hole (BH2)...

This happened a long time ago, and I haven't found the answer. I posted a post on the Internet, and no one gave an explanation, so I really hope to find the answer. A magnet, no matter which pole is facing up, will rotate counterclockwise, as shown in the figure below. The magnet will not spin...

when an electron is excited to the conduction band is it move further from the nucleus? Are free electrons in the conduction band further from valence electrons? I saw this picture that seems problematic to me. what do you think?

The Kallen-Lehmann representation is a (non perturbative) result in QFT that is proved with what seems to me like very minimal assumptions: https://en.m.wikipedia.org/wiki/Källén–Lehmann_spectral_representation According to this wiki page, in gauge theories something goes wrong and you can no...

If we throw empty but sealed glass bottle in water it will float with 60% of it's volume above the surface of water. What is average density of floating bottle and what is it's volume? Mass of bottle is 0.4 kg(mass of air inside of bottle is irelevant). It's easy problem but I can't get right...

Does anybody have any info on this fan controller? I don't even know what to Google, because I don't know what that second character is. Any help?

I searched, "is infinity possible?" Because I was coming up with some thoughts which seemed logical (I hope) so I was compelled to find others discussing the topic to see if I even came close to several different answers.

During the procedure, 30% of heat is lost. So that means that 70% of water+container is contributing to melting the ice, right? And the other 30% contributing melting the ice is down to, well, the "heat being lost to the surroundings" (not sure what this really means). We compute the sum and...

so this is what the FBD is.... but to be fair, to me this one looks as if the normal force in the direction of the radial line, yet it isn't???? here in the solution, it's not along the radial line, whys that???

So, my idea would be that this happens at an angle ##\theta = \frac{\pi}{2}##, or quarter of a whole rotation. At this point, the wheel starts moving right again, after going to the left. Due to it's inertia, the piece of mud would want to keep it's current direction of motion and therefore fall...

I'm attempting to repair my Ergotron Workfit station. After taking apart, I discovered the problem. A single nylon rope split, releasing the spring's tension. Because it is past the warranty, the manufacturer is recommending I toss the whole assembly and buy a new $650 one. Doesn't seem the...

When calculating calories of a food.. It is sort of well known that carbs have 4 cal/gram, protein has 4 cal/gram and fat has 9 cal/gram. I wanted to do an experiment to determine these constants 4,4,and 9 I looked at soup, peanut butter, and a protein mix to get the values from the labels per...

I mixed some fertilizer based on a soil test. The chemistry contained Ammonium Sulfate prills (NH4)2SO4, Potassium Sulfate prills K2SO4, Superphosphate CaH4P2O8, trace of Manganese Sulfate MNS04, and trace of Boric Acid H3BO3. I mixed it and wiped my hands on the front of a white tee shirt...

Hi PF. I desire deeper understanding of fundamental physics, and quantum mechanics can be a challenge for me (compared to other topics in physics). I read in the intro of the physics textbook chapter that QM explains many phenomena, e.g. why copper conducts electricity and glass does not. In...

Suppose there is a series of flights from A to B to C to D. Often the fare to do this is less than the fare from B to C. Can anyone explain why this pricing is common?

Say there is a subject of 80 marks and I have 8-10 marks question about "How MPLS works". I will list the information that I am planning to write(but I want your feedback on what I should write?) What my local author textbook (that our teachers use to teach) writes-: 1) gives 1 line info...

If a magnetar is a neutron star, how do the neutrons composing the star generate a magnetic field? A neutron has zero charge, so it generates no magnetic field.

I tried setting the Universal time T = Tp as when T = 0 there was no universe and thought Tp would be the first instance of the universe, but I still can't figure out how equation (3.1.3) implies that M0 = Mp/2

Hello! I found this circuit element below in a drawer marked "IR detectors" (which I must have written on it myself, a long time ago...although I must admit don't remember doing so #OldAge). First of all, I'm trying to figure out what, exactly, it is. My initial assumption was that it looks...

Hello, human people's. I noticed a strange phenomenon while playing electrochemistry. - i used 2 strips of aluminum foil as electrodes in sodium sulfate solution, 1 for positive terminal and other for negative. Applied 5 volts, essentially zero current flew. - i used 1 strip aluminum for...

I see there has been threads about Blackbird and "Down Wind Faster Than The Wind" operating principle in general, and I see a good number of people (most?) in those threads seemed to pick up some understanding of how it actually works. So that's a good start and gives me hope. I had never heard...

I a car,why do you move back when the car accelerates forward. You move forward when the car accelerates backwards,You move right when the car turns left on a bent road, you move left when the car turns right on a bent road. What actually makes you move in the opposite direction of the car.

This is an extended thinking portion in my textbook, and I would really like to know why this is. I'm not too sure what the answer to this is, and unfortunately, there is no answer to extended thinking in my textbook. I've been trying to figure this out for some time now and I'm completely stumped.

Hi, PF The scientific calculator I have is a Casio fx-82MS. At the keyboard, the ##\fbox {^}## button is the one provided to calculate powers. My doubt is not my calculator: is a sentence at a native thread: "##x^{\blacksquare}## es la función" (the function is ##x^{\blacksquare}##). The...

The equation is the only equation discussed in the textbook. Is there a hint of how I could start this?

While using an ordinary gas duster (difluoroethane) to clean some electronics, I noticed something weird (see linked videos): After spraying the gas duster and placing it on a hard surface e.g. countertop, the can emits a fizzing noise. Picking up the can causes the fizzing to stop. The process...

https://apod.nasa.gov/apod/ap210106.html It sure looks like some strange life form to me.

a) I think in the beaker with A and B, A must be the top fluid and B must be the bottom. The ball sinks through the top layer but not through the bottom. In the second beaker (B and C), it does not sink through either layer. Therefore, both B and C are more dense than the ball. So B must be...

How can I solve a ciruit mystery box only knowing there are 5 identical resistors inside. I have two boxes to solve, one they're all in serie and the other is a combination serie and parallele. Each mystery box has 6 nodes and i can connect 2 nodes at a time to an ohmmeter. If i take the one...

How can I solve a ciruit mystery box only knowing there are 5 identical resistors inside. I have two to solve, one they're all in serie and the other is a combination serie and parallele. My mystery box has 6 «plugs» and i can connect 2 plugs at a time to an ohmmeter. I've been trying for days...

I'm baffled. 10 days ago or so, I was preparing to wash my clothes. I grab a pair of pants and see a wet spot on it that was slightly smaller than the diameter of a Coke or Pepsi can. I believe it was a circle shape. Having not worn that pair of pants for days and not having had it come...

I just found this in my store room. Anybody have any ideas what it is?

I have a problem regarding Kinetic Energy which as we know is 1/2 m v squared. Say I have a 1kg mass moving at 10 meters/second. I have a 1 Newton rocket which I attach to the back and it burns for 1 second accelerating the mass by 1 m/sec/sec to 11 m/sec. The KE originally was 50 joules and it...

Liquid diamonds apparently may form in gas giants where huge atmospheric pressure compresses carbon into diamonds that are then liquified as they fall downward into zones of increasing pressure. I thought a diamond was a crystal structure of carbon. How can this also be a liquid...

Hello, When I tell this story, I usually get brushed aside for being senile but people who know about physics might be more useful. About a week ago I was woken up with an alarm from my clock-radio. That was odd as I had never used the alarm function. Unable to find the cause, I assumed the...

During the derivation of the dielectric function of a plasma (Kittel 8. ed. chap. 14), this somewhat mysterious quantity ε(∞) is inserted to account for the high-frequency dielectric contribution of the ionic background. In some ways, I see how this is related to the "external" charge density in...

I am hoping that people here might be able to provide insight into what context/s this equation might be relevant, particularly the contents of the brackets. I am aware it is a strange request, related to puzzle solving, but perhaps someone can help guide me in an interesting direction.

Hello, I would like to understand as well as possible what (quantum) coherent states are. Can anyone advise on what books (or other materials) I should read? Please assume I have an introductory level in Quantum Physics (where by "introductory" I mean the material introduced in books like, for...

So, this may be a really stupid question, and I strongly feel as though I'm missing something here. How can it be that objects of different masses have the exact same acceleration when mass is in fact resistance to acceleration? And then, if in (a vaccum) I throw upwards M and m ( a bigger and a...

A year or so ago, I had a licensed electrician come in and retroactively fix up some of my wiring (My amateur fingers did nothing near the panel, just extensions to existing lights and outlets). He ran new cable and installed a couple of new breakers for them. My basement has been gutted to...

I was reading the chapter kinetic energy and work where I saw a derivation in which it was proved that work done=change in kinetic energy, so i understood from this derivation that work done is energy transfer by means of force but in this book kinetic energy is introduced earlier so as to find...

Background: My understanding is force and mass are two different things. Mass is how much matter is in a body Force is mass multiplied by an acceleration. Here on earth, that acceleration is 32.2 Ft/s2. Therefore, for the same mass, there can be different forces depending on the...

I am trying to understand “divergence” by considering a one-dimensional example of the vector y defined by: . the parabola: y = -1 + x^2 The direction of the vector y will either be to the right ( R) when y is positive or to the Left (L). The gradient = dy/dx = Divergence = Div y = 2 x x...

So something weird just happened along the way in my experiment, here is a little background of what I'm doing. I have created a roughly 3x5mm inner diameter rectangular shaped channel for MHD liquid testing for one other project of mine, it's a simple conduction type MHD pump where the...

What part of double slit mystery remains considering single slit can produce interference pattern as well? Does holography not fully explain those patterns behind any number of slits as a sort of "encoded image" of the slit(s)? Does the word "focus" have any meaning in these kinds of experiments?

Clarification: The statement in the title is actually from the solution to the homework question, as given by the textbook (you can see the whole thing below under "Textbook solution"). The solution doesn't explain everything, which is where my confusion comes from. Usually in my classes we...

I recently looked at a transcript of a 1991 interview of Hans Bethe, where he recalled the suggestion that an atomic bomb could ignite the air. "Teller at Los Alamos put a very good calculator on this problem, [Emil] Konopinski, who was an expert on weak interactors, and Konopinski together...

We know the answer, but don't know how it makes sense given trigonometric principles. Borrowed from HiSet free practice test