Reference Definition and 1000 Threads

Hi, So apparently electrons don't orbit the nucleus of atoms so I'm assuming the lack of movement means that no energy from the atom is radiated away from an atom due to minuscule gravitational waves, over the life of the universe. But gravitational waves have got me thinking about reference...

Whenever we define torque from a frame of reference, is it necessary for the frame to be inertial? Please explain because I am unclear on this.

hi all i need a good Reference about mathematics my level in mathematics as zero

Define a function CoordTransform() that transforms its first two input parameters xVal and yVal into two output parameters xValNew and yValNew. The function returns void. The transformation is new = (old + 1) * 2. Ex: If xVal = 3 and yVal = 4, then xValNew is 8 and yValNew is 10. My code...

Homework Statement A platform rotates with ##\omega=10## rad/s around ##z##-axes. A ball is connected, with a yarn to ##z##. Its distance to the axes is 15 cm and it rotates with ##\omega=10## rad/s. There isn't friction between platform and ball. Suddenly, the angular velocity of the...

Dear Physics Forum personnel, I would like to seek your recommendation on a good, introductory textbook in the probability theory (non measure-theoretic treatment) that contains both the applied and theoretical treatment of the subject. My goal is to advance into the measure-theoretic...

Hello, My understanding is that a a frame of reference is a theoretical framework that is used to describe the motion of an object allowing for measurements of position, distance and time. A frame of reference always implicitly includes a coordinate system (cartesian, spherical, cylindrical...

Hi, I've submitted my graduate application for some competitive programs and have had all my reference letters submitted. The deadline is now officially gone. However, I have not had my thesis advisor submit a letter of reference. I've talked to some of the programs and they have sent an...

Is the inertial frame of reference the same thing as space time?

I'm currently doing a student project at uni and I'm trying to design magnetorquers for cubesats.Before I make the prototype I need a simulation of what will happen.The problem is that for my calculations,I need to change the frame of reference of the geomagnetic field.So basically I need to go...

my book says " the total momentum is zero in the centre of mass reference frame.This should not surprise you" but ITS NOT INTUITIVE FOR ME. I am considering a completely elastic collision. 1. I know the v_cm is const because there are no ext forces on the system of the two masses undergoing 1D...

Hi there, I'm currently looking for a book on ADM formalism in General Relativity. I know that it's definitely not a method really taught so wouldn't be in many textbooks, but was wondering if anyone knew of any great books to use! Thanks in advance

So, a friend asked me this question in school and I've come up with an answer, I'm just not sure that it is right. Say you have a charged particle moving perpendicular to a magnetic field. There will be a force acting on it given by F=qvB. Now suppose your'e moving along at the same velocity as...

I've read Hawking's introduction: http://arxiv.org/abs/hep-th/9409195v1, which are nice. I would like something that explains the other singularity theorems and how they are related to Big Bang. I've tried reading Hawking & Ellis but I can't understand most of the definitions.

I've applied to a particular university for fall 2016 graduate admission. The deadline for my referees to submit the application is December 01. One of my referees is currently extremely busy and has asked me to request the graduate administrator to contact him regarding the reference letter...

The reason we can choose a frame of reference arbitrarily is that a physical system is not dependent on an absolute position, orientation or time. According to Noether's Theorem, the invariance of a system under a change of position is equivalent to the momentum conservation law. In the same...

I understand that if someone is traveling away from Earth at a very high speed, time will slow down for the traveler relative to the people on earth. However, why is it not the other way around? If there is no universal reference frame, could this situation not also be thought of as the traveler...

Homework Statement Recently, I have been wondering whether forces are independent of reference frames(inertial and non inertial). From Newton's law we know that the second law is valid only for inertial frames. But what about the non inertial frames. Let ∑F be the net force on an object in an...

In an inertial frame of reference let numerous standard rockets that load synchronized standard clocks place on all the space lattice. Simultaneously the rockets start to move with same intrinsic acceleration to the same direction. In other words there exists a common instantaneous inertial...

I am looking for a book that starts at the standard ZFC axioms and progresses to the point where some recognisable non-trivial mathematical statement is proved. By recognisable I mean something that you may encounter in school/early university level and is not purely set-theoretical (e.g...

I am requarid to submit reference letter with complite reference data (of my recomendator) could you tell me what dose reference data means? Is it just list of publications of something else? o_O

I had this questioning about the light clock on another thread, and DaleSpam suggested that I open my own thread, so here it is. I was asking if the light clock mind experiment was not contradicting the reference frame principle. I added that to my drawings: And DaleSpam answered this: So...

Homework Statement Homework Equations Xcm = (x1m1+x2m2) / (m1+m2) The Attempt at a Solution ok so I'm having trouble understanding what's happening in the question... when the penguin moves, is the sled also moving? If it's friction less ice then if the penguins moves L, the sled will...

OK, I'm sure I'm just not thinking about this the right way, so please point out my simple mistake. Imagine a charged particle and 2 observers. Observer S is stationary relative to the charged particle, so sees no magnetic field from it. Observer A moves back and forth in front of the...

If light travels in a straight line , why can't we use it as absolute frame of reference? This thought experiment is done in the absence of external forces and gravity. One person standing inside a box ,sends a photon parallel to the bottom of the box from one end to another end , whether...

Claim: The acceleration (both direction and magnitude) for any object is the same in any inertial reference frame. Is this claim true? I think it is, but someone mentioned to me that time may be an issue as it's not agreed upon in all inertial reference frames. I'd appreciate any references...

Does anyone know of a thermodynamics tables for reference to recommend me?... It would be preferable in metric system or in both, british and metric. I searched in the past posts and, I didn't find information about this issue. I found this tables on Amazon, but I prefer to hear from your...

Leaving Earth at constant acceleration will make time on board go slower. Acceleration will take the ship closer and closer to c Question is: How long will acceleration act on the ship? The time as measured on Earth or on the ship? The final v will be greatly different. Of course, given enough...

Hello PF. There are two lightning flashes , and two stationary observers. Observer 1 who is equidistant from the flashes, sees them as simultaneous Observer 2 stands one step to the side of observer 1, and is not equidistant. He sees the flashes as separate, the light having unequal distances...

Which of the two books would you pick as an undergraduate engineering student if you were to study the subject of Heat and Mass Transfer entirely on your own? 1. Heat and Mass Transfer: Fundamentals and Applications by Cengel & Ghajar 2. Fundamentals of Heat and Mass Transfer by...

Hello all, was it ever a point of discussion in cosmology, quantum-theory, mechanics, etc. that there is a fundamental difference in describing a physical process in a 2n-grade (4th, 6th, 8th-grade) frame of reference in comparison to a 2n-1-grade (3rd, 5th, 7th-grade) frame ? Thanks in...

I'm just beginning physics and teaching myself classical physics from an intro physics textbook and in the 2nd chapter it described reference frames. This got me thinking. My reference frame is the earth, as that is what I use to describe position, displacement, ect. But what is the reference...

Homework Statement A car is moving toward north with a speed of 35 km/h. A truck travels toward west with a speed of 42 km/h. Which is the speed of the caravan according to the car's driver? Homework EquationsThe Attempt at a Solution The solution given by the book is 15 m/s with direction...

Hi, This might sound very basic and but i am just starting to learn physics. I an lecture by prof. walter lewin, he descibes the hunter and monkey scenario. The monkey jumps from the tree as soon as the hunter aims and shoot his gun. the bullet hits the monkey anyway. In calculating the time it...

I saw random question somewhere on the internet a couple of weeks ago and it got me really thinking about it. Supposedly you got a remote control miniature toy helicopter hovering inside a bullet train, if the bullet train suddenly started and accelerated to 200km/hr in 3.5 sec, will the toy...

I had a little thought experiment, in which there are two objects with the same masses near each other (same height) on freefall. If I set up a point that is on an instant besides the two masses and call it the center of torque, I get that the torque produced by the nearest one's weight is...

I know that when we have to identify the nodes for solving a circuit with nodal analysis we always have to designate a reference node (which will be the ground node) as a reference for measuring the others' voltages. However I was practicing this and I found this example on...

I am a Ph.D. student just beginning my research. Recently, I found several papers about surface and interface interesting, so I want to know more about this area. However, I cannot find any specific review which can give me an overview of this area. Can anyone give me a link to such literature?

I know that most of you have grown up in this digital era, but me myself, I am a old school man, and, I usually use reference books. Today, I would like to recommend a small and practical book. Have you ever been working in an installation, in the middle of the Amazonian jungle or in the...

I'm applying to grad schools and my undergrad has a very small Physics department - only 3 professors. I am having at least 2 of them write me letters of reference, but in regards to my third letter, should I ask the other professor, who I've only had a few classes with, or should I ask my...

Hello, I will be applying to universities in England for fall 2016 entry and I have one particular concern. I have studied independently instead of attending an ordinary high school, but I've taken and will be taking various exams. Because of this I have no one who can write a reference letter...

In the usual derivation of time dilation in special relativity, we have two frames of reference, A and B, moving relative to each other with velocity v. In A's frame, a light beam is directed vertically upward toward a mirror and reflected vertically back down. In B's frame, the light follows a...

Hi, I have been studying lorentz force . The book says force experienced by a charge in magnetic field is But velocity is a relative concept . In one frame of reference(inertial frame) I might observe the charge moving with some velocity and in the 2nd frame(inertial too) I might observe the...

Hello, Please: • Assume a universe void of all matter • Visualize 2 parallel paths, 10 meters apart. Let’s call them x and x' • Vessel X is moving along x and vessel X' is moving along x' • Vessel X has a mass of 1 metric ton and vessel X’ has a mass of 2 metric tons • At t0 the...

Hi all, I'm curently meeting the following problem and can't figure it out by myself. Assume we have to vehicles in space, a target and a chaser spacecraft . The target spacecraft defines the RTN frame of reference. Given the position and velocity of the chaser in RTN-coordinates, how can I...

Hello. Can i know which reference book is the best for physics? I am a foundation in science student

Homework Statement Show that Newton's Second Law is NOT valid in a reference frame moving past the laboratory frame of problem 1 with a constant acceleration? Problem 1: In a laboratory frame of reference, an observer notes that Newton's Second Law is valid. Show that it is also valid for an...

Homework Statement Show that Newton's Second Law is NOT valid in a reference frame moving past the laboratory frame of problem 1 with a constant acceleration? Problem 1: In a laboratory frame of reference, an observer notes that Newton's Second Law is valid. Show that it is also valid for an...

Homework Statement Particle X moves with a velocity of 15 m/s[R]. Particle Y moves with a velocity of 5.0 m/s[L]. What is the velocity of particle X with reference to particle Y? The correct answer is 20 m/s (R). I do not understand what velocity in reference to particle Y means, and how to...

Why ISO-OSI model is considered as a reference model?