Reference Definition and 1000 Threads

Last thread that I initiated was titled `Simultaneity is directional while Time Dilation is not', which presented a scenario for the Non-directional property of Time Dilation in STR. Which I think, needs to be reconsidered. And I believe this is the reason why `STR can only be worked out when we...

Post any thoughts or ideas here.

The speed of light, the term "light year", and reference frames. Hi everyone. This is my first post, and I post out of desperation. A friend of mine and I were casually discussing Time Dilation, interstellar travel, etc. when we came to a point we fundamentally disagreed upon. Neither of us...

Please excuse my ignorance - I am a biologist by training - but this is one of those questions that just keeps bothering me and I can't find the answer with Google/Wikipedia. Take as our example the ocean currents on the Earth caused by the Coriolis Effect of the Earth turning. When I read up...

I have been reading Einsteins Relativity and a simple concept in special relativity is tripping me up. I have heard that an object can never reach the speed of light. To which observer is this speed limit seen by. I know your answer will be "By all observers" but that is what I don't get...

The first law of motion says that it takes force to accelerate something. The second law of motion says that F=ma. So now my teacher says that the first law is for inertial reference frames, while the second is for non-inertial reference frames. This really annoys me because I don't...

If one wants to calculate the elapsed time from the perspective of an object A moving at velocity, v, for time, t, relative to a stationary object B, all you have to do is calculate: \int_{t_o}^{t_f}\frac{t}{\gamma} Of course, \gamma has no dependence on t because v is constant, so we get...

Hi, Currently, I need to read some reference about Integrable System, but I am stuck in Riemann Surface, genus, divisors, and Riemann Theta Functions. This makes me anxious. Is there introduction or pedagogical reference on this topic? I think I can spend some time read it during winter...

Hi, I've been listening to a Professor Jim Al-Khalil's scipod on time travel. I think this guy is bloody excellent by the way. http://reader.mac.com/mobile/v1/http%3A%2F%2Fwww.jimal-khalili.com%2Fpodcast%2Fjim.rss Anyway, He said to an observer on the Earth a clock on a...

a frame of reference is moving with a constant velocity with respect to a inertial frame of reference,then moving frame will be inertial itself?

Hello; I'am asking about the best textbook or refrence in particle & high energy physics ?

The experts say the age of the universe is known with considerable accuracy. What frame of reference are they using and why doesn't it violate the idea of relativity to claim to have a preferred frame?

Hello there I have 2 questions: 1. Can one change the coordinate system of torque vectors through a homogeneous transformation matrix with both rotation and displacement? 2. What's the procedure to add two torque vectors about different axes? Thanks in advance, João

An inertial frame is one which is not accelerating. i.e if I'm sitting in an accelerating bus or plane I'm not an inertial observer however if I am in a bus or train traveling at a constant velocity i.e zero acceleration then I am an inertial observer. One thing Id like to ask here is that...

- http://www.physicsinsights.org/glossary.html I'm often unsure whether people are using "frame" to mean a chart, or a basis field of tangent vectors, or a basis for an individual tangent space. Have I got this (more or less) right? (1) A MCRF of a pointlike object is a function that...

Is there really an absolute reference frame?? According to mechanics as we understand today, all reference frames are equally valid in analysing in the universe, whether measurements are taken relative to the earth/sun... However if all reference frames are equal, why can't we take...

Hi All! I found discussions on this here while researching the subject to see if anyone else has attempted to explore the subject. I saw that several people asked questions pertaining to this, but the question was never really answered. It seemed unanswerable. While many discussions of...

Hey all! For awhile, I have been looking for a .pdf version of a math notation sheet, similar to these sites: http://www.rapidtables.com/math/symbols/Basic_Math_Symbols.htm http://en.wikipedia.org/wiki/List_of_mathematical_symbols I like the way they have the notation in LaTeX, have a meaning...

Homework Statement Challenge: a rather eccentric group of astronomy students wanted to celebrate the impact of the Shoemaker-Levy comet on Jupiter by holding a party of sufficiently long duration that their celebrations were simultaneous with the impact of the comet in all inertial reference...

Homework Statement A frame is accelerating uniformly along the x-axis relative to an inertial frame (x,y,z) with acceleration a.Find the transformation between the frames given that the origins concide at t=0. Homework Equations The lorentz transformations cannot apply here ,but what...

Hi friends, I need the average speed of sound in some common solids, such as Si, Cu and Al, over temperature ranges from 100K to 500K. After 5 hours of surveying acoustic and physical properties handbooks and googling the web, what I find is almost nothing. Does anybody know a...

Hello -- I have some reference object R (e.g. a protein), and I've got two transformations t1 and t2 (e.g. a transformation = quaternion + translation). In my case, t1 and t2 were obtained from symmetry operations. So after applying t1 to R I get object T1, and after applying t2 to R I get...

Homework Statement [PLAIN]http://online.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys211/oldexams/exam2/sp10/fig3.gif A 4.0 kg circular disk slides in the x-direction on a frictionless horizontal surface with a speed of 5.0 m/s. It collides with an identical disk that is...

Hi I am having trouble figuring out what to do with negative reference voltages in my circuit. I attached my problem(Problem 3) and I know that some current will be drawn out of the ground and I think all of the diodes will be on but I am unsure how to approach this problem.

Hi, guys! Gold is usually used as reference element to calibrate the detector in XPS due to the charge effect, why is Gold so specific? So what element can be the reference element for XRF and LIBS? Thanks a lot!

Hey, this is my first post. I am a biology major so I know pretty much nothing about physics, yet sometimes it interests me way more than chromosomes do. So, given that I know nothing about physics, this is probably going to sound like a stupid question. But I've always wondered how it is...

Homework Statement See figure attached for problem statement, solution provided and my solution. Homework Equations The Attempt at a Solution I'm getting confused about the reference point for the potential. First find the potential at point z with reference at infinity...

Hi! :smile: Need some help here. Can we perceive time dilation and length contraction in a non-inertial reference frame? If we observe a reference frame experiencing acceleration close to c, do we see the same effects as in an inertial reference frame?

This website has an animation that shows the difference between sidereal reference frames and synodic. http://www.sumanasinc.com/webcontent/animations/content/sidereal.html The motion of the moon is circular about the earth, yet apparently the moon has an apogee length that is 50,000 km...

Homework Statement A mass of 2 kg lies on a horizontal table that is placed in the back of a truck. The mass is held in position by a string and a force of 6 N acts on it in the -y direction. The truck then accelerates in the +x direction. As a result, an observer in the truck sees that the...

Problems related to conservation of momentum/energy can be solved by taking reference frame which is stationary to center of mass or which is stationary to ground/observer. So when to use what frame or which frame is beneficial in which case/type of problems? I m confused !:confused:

Breit Frame of reference ("Brick Wall") I am having a lot of trouble understanding breit frame of reference.I was trying to solve griffiths problem 3.21 (1st ed.): Consider elastic scattering- A+B----->A+B If particle A carries energy E, and scatters at an angle theta in the CM, a) what is...

I have a question about the correct way to write a reference to a private communication. The other day I was making some corrections in the proof of an article that will soon be published. One of the questions/comments from the editors office was that regarding a referenfce to a private...

Can the kinetic friction be in the direction of acceleration? I am thinking of the example of a box on a flatbed truck accelerating to the right from rest. The box accelerates to the left due to the inertial force as seen by an observer on the truck where the kinetic friction is opposite to the...

Homework Statement A 110-m-wide river flows due east at a uniform speed of 3.3 m/s. A boat with a speed of 8.6 m/s relative to the water leaves the south bank pointed in a direction 37 degrees west of north. What is the (a) magnitude and (b) direction of the boat's velocity relative to the...

From what I can glean, since kinetic energy = 1/2 mv^2, it follows that a doubling of velocity requires a quadrupling of energy. One joule is required to accelerate a 1 kg mass from zero to one meter per second per second. ie 1m/s2. Now, to further accelerate the mass to 2 meters per second...

Let’ say; “A” can see and measure a stone falls to the Earth let’s say 10 meter per 1 Earth-second. “B” lives at Mercury and can see the same thing. But “B” would do not see the exactly the same, because seen from “B’s” viewpoint time / distance is not the same as for “A”. Let us say...

A swimmer who achieves a speed of 0.75 m/s in still water swims directly across a river 72 m wide. The swimmer lands on the far shore at a position 54 m downstream from the starting point. (a) Determine the speed of the river current. (b) Determine the swimmer?s velocity relative to the shore...

in at 0:47:00 Susskind begins discussing accelerated reference frames and notes that they relate to hyperbolas rather than parabolas. I understand the concept and need for the proper acceleration to be asymptotic at C. Susskind seems to infer that an observer in the accelerated frame will...

A large heavy box is sliding without friction down a smooth plane of inclination Ɵ. From a point P on the bottom of the box, a particle is projected inside the box. The initial speed of the particle with respect to the box is 'u' and the direction of projection makes an angle α with the bottom...

I have sensor that produces differential output. I saw in the sensor schematic that they have used 2.5v DC as reference in the output minus terminal. I am taking sensor output as differential that both positive and negative(2.5DC ref terminal)in count. I got output as 1v of DC when the sensor is...

What is a good, solid reference text for multivariable calculus? Ideally something you'd get by following on from Spivak's Calculus into 2/3d/Vectors etc. I've already done the course, but it's sort of slipping my mind these days - I've mostly been doing chemistry subjects, and they're not...

Hi, I am a grade 11 student preparing for the IIT-JEE. I would like to know about some good books on thermodynamics. Young, Sears Zemansky & Resnick/Halliday/Walker don't go into much depth on this topic.

Homework Statement Let's say that there is a bicycle traveling forward and we only see it from behind. As it rolls to turn, it induces some accelerations. If we were to measure those accelerations on the bicycle frame itself, we would see a Lateral Acceleration (lets call it Aym) and and a...

I'm a Grade 11 student preparing for the IIT-JEE. Can anyone suggest me good reference books for PHYSICS? I looked up H.C. Verma but did not find it appealing at all.

I'm a student preparing for IIT-JEE. Can anyone suggest me some standard reference books for physical chemistry?

V. A. Belinskii and V. E. Zakharov, Integration of the Einstein Equations by the Inverse Scattering Method and Calculation of Exact Soliton Solutions, Sov. Phys. JETP 48, 985 (1978)I cannot access to in via the library in my department. But I need it in my research. Sad...The website...

I found this article: http://www.csa.com/discoveryguides/gravity/overview.php" The article says gravity moves at the speed of light. But does gravity do so in any reference frame, like light does? Thanks, Jake

Hi, I' am wondering If someone knows a reference for a full/complete list of John von Neumanns publications. I have been unable to find one, but something like that should really exist right? thanks for the help in advance Oh and I am not sure whether this is the right subforum, but it...

During the D.J. Griffiths, Introduction to Elementary Particles, the author introduces unpublished references "Classical Chromodynamics" and "Bare Bones of the Classical Theory of Gauge Fields", Reed College, Portland, O.R. which is written by Wheeler, N. A. (1981). Where can I find this...