What is Reference: Definition and 1000 Discussions

Reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to refer to the second object. It is called a name for the second object. The second object, the one to which the first object refers, is called the referent of the first object. A name is usually a phrase or expression, or some other symbolic representation. Its referent may be anything – a material object, a person, an event, an activity, or an abstract concept.
References can take on many forms, including: a thought, a sensory perception that is audible (onomatopoeia), visual (text), olfactory, or tactile, emotional state, relationship with other, spacetime coordinate, symbolic or alpha-numeric, a physical object or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in cryptography.References feature in many spheres of human activity and knowledge, and the term adopts shades of meaning particular to the contexts in which it is used. Some of them are described in the sections below.

View More On Wikipedia.org
Recent contents Top users
  1. Andre' Quanta

    Distinction between coordinate and reference frame

    How is it possible to distinguish a change of coordinate from a change o reference frame? I had this problem while i was studying Rindler' s coordinates: is it only another way to describe a Minkowsky space-time region or does it rappresent a region of the space time as described by an...
  2. R

    Time dilation in accelerating reference frames

    Sorry for the lame question, but I was wondering if someone could help answer the following. I have two synchronised clocks which I place on two different space ships which then accelerate away from me at the same rate and time until they reach a given speed. Ship A then slows down to be at...
  3. Stephanus

    What breaks the symmetry in the twin paradox?

    Dear PF Forum, Sorry if I ask again, because I want a detailed information. Does the universe has a frame of reference? Two twins. A stays, B "travels". (Travel here is confusing, B will say I stay and A travels) and B "turns around" and come back. B ages more slowly then A. Q1: Why? A1...
  4. ecfedele

    Need some reference on centrifugal pump design

    Little bit of a disclaimer: if you take a look at my first (introductory) post, you'll see that I'm working towards aerospace engineering; therefore, this is leaning towards turbopump design, but for the time being I'll start out slow. Basically, I'd like it if anyone could help me get a sense...
  5. H

    Frame of reference and the varying mass problem

    Hi Friends , I had a discussion with a funny person last night. He said the following argument : Suppose there are 21 objects including the one object under consideration. Each of the 21 objects move with a velocity. Since there are 21 objects, for the object we are considering has 21...
  6. Stephanus

    Does the Universe Have a Preferred Frame of Reference?

    Dear PF Forum, Again the same question about preferred frame of reference. I have read several threads in Physics forum, but I think this question belong to cosmology. And I have searched in Google and in PF forum threads, so, I'll ask some confirmation here. 1. Does the universe have a...
  7. O

    Inertial and non inertial frame of reference

    When I was surfing on a group in Facebook, I found two concepts very difficult to understand by reading the discussions in comments. Those concepts are inertial and non inertial frame of reference. Please make me understand these two concepts in simple words. Please don't suggest links as I...
  8. Calpalned

    Velocity on a moving reference frame

    Homework Statement I am reviewing for my midterm and I just want to quickly understand a concept. It seems that velocity does not depend on the original reference frame. For example, let's say spider man is standing on the ground next to a 78.4 meter tall building, and it is known that if he...
  9. Alex_Neof

    Frame of reference of bicycle rider

    Homework Statement A wheel of a bicycle weighs 1 kg, all of which is at the rim. The diameter of the wheel is 0.7 m. If the bicycle is ridden at the speed of 3.5 m s–1, then in the frame of reference of the rider: i) Calculate the angular speed ω of the wheel. ii) Calculate the momentum of...
  10. T

    Difference between frame of reference and coordinate system?

    Homework Statement Our teacher said we can NEVER do an F=ma problem from an accelerating, or noninertial frame. (He said there are ways to do it, but we can not do it in his class), and I'm confused becuase often times he makes the "system" or makes a "free-body diagram" around an accelerating...
  11. S

    Trigger for a Zn oxidation reaction in a battery Reference

    Who is the trigger of the oxidation reaction. Copper which attracts electrons from the Zinc or solution which makes Zinc losing electrons and become positively charged. I am struggling to understand what actually makes Zinc to enter the solution and leave 2 electrons behind. If there is no wire...
  12. J

    Feel awkward using my current manager as a reference

    I'm working a contract job and was offered a salaried job at the company but turned it down after holding on to the offer until they put pressure on me to make a decision. I think they knew that I was holding on to it as a backup plan while trying to get an offer somewhere else. Well, I pretty...
  13. S

    Inertial and Non-Inertial Reference Frames

    Hi All Physics newbie here... Just a quick question regarding Inertial and Non-Inertial Reference Frames. From what I understand: Inertial = One that obeys Newton's Law of Inertia. Moves at constant velocity in one direction Non-Inertial: One that accelerates. Right? So, I read somewhere that...
  14. A

    Velocity frame of reference in lorentz force equation

    Hi, I am new here, but there is a question that really bugs me :-(. In Lorentz force why was the velocity defined as relative to the observer and not relative to thesystem generating the magnetic field. By defining it relativ eto the system relativity is not needed to explain how an observer...
  15. BTBlueSkies

    Free Fall vs accelerated reference frame question.

    I had a though last night that kept me awake trying to figure out what I was trying to understand. I have been out of school many years now so I have forgotten much.. Here is my question. Lets imagine there is a 30 meter diameter hole (complete with a vacuum) in my front yard that goes through...
  16. Calpalned

    A mass m slides in a moving reference frame

    Homework Statement An inclined plane, fixed to the inside of an elevator, makes a ## 32 ^\circ ## degree angle with the floor. A mass m slides on the plane without friction. What is its acceleration relative to the plane if the elevator accelerates upward at 0.50 g? Homework Equations...
  17. eis3nheim

    What is the best referece book to study atomic structure?

    what is the best referece book to study atomic structure and electronic structure of atoms ?
  18. B

    Fixed and Moving Reference Frames for adding speeds

    Hi Folks, I have some misunderstanding how one can add velocities of different coordinate systems. Consider a planet gear rotating about its own axis and also rotating on its carrier so that the so called velocity of the planet gear relative to the carrier is the planet local velocity minus...
  19. I

    Excel 2011 for Mac Mixed Reference Macros Issues

    Homework Statement Hello! I would be grateful for your help. I've tried many many times to record a mixed reference macro on my mac, and it doesn't record a thing. No problems with recording separate macros with relative or absolute reference. Problems description: I have few sheets with...
  20. P

    The surface of the Earth as a reference frame

    At about 05.30, Dr. Lewin makes a small calculation to find the centripetal acceleration one experiences due to Earth's spin (at the equator). He then says that because of how small the magnitude of this acceleration is, we could consider the Earth's surface to be an inertial reference frame...
  21. N

    Reference request: Supermanifolds with open charts approach

    I've decided to work on some topics about supersymmetry for my undergraduate thesis. My background is that I have had a one-semester course in differentiable manifolds, plus typical undergrad math courses, real analysis and module theory (graduate algebra). So, I went to the library and found a...
  22. T

    Understanding Torque and Reference Frames in Rotational Motion

    Hello, I have a question regarding the concept of torque and reference frames. Say for example I have a rod of length L and that the rod has it's right side anchored to act as a pivot point. Now let's say that I input a force on the left side of the bar in an upward direction. Assuming that...
  23. L

    What is a Frame of Reference in Physics?

    I'm studying special relativity for the second time and there's something I think I didn't get since I studied classical mechanics: the idea of a frame of reference. I think the underlying idea is that of a point of view, so that we want to study some phenomenon, but we have to observe it so...
  24. Unified28

    Both frames of reference predict the other is slower -- proof

    While trying to understand how each frame of reference predict that the other is slower, I discovered what seems to be something unsymmetric. It looks as if it is possible to determine that a frame of reference is not one truly standing still. But that's impossible right? I'm really interested...
  25. D

    Understanding Classical Physics: Frame of Reference

    So I understand that in classical physics, movement only makes sense with reference to another body. So my car moves relative to the surface of the road, for example. But it seems that with acceleration, things appear to be more complicated than that. Let's say we have two objects in space...
  26. L

    Accelerating charges and frames of reference

    An accelerating charge radiates light. But in its own frame of reference it is stationary. So it does not emit light. How is this explained? Extreme Example: A charge inside an elevator is falling in a gravitational field. The elevator is lined with a light sensitive sensor that triggers a...
  27. H

    How Does the Choice of Reference Point Affect Calculations in Torque Problems?

    Homework Statement A uniform plank of length L = 6.0 m and mass M = 90 kg rests on sawhorses separated by D = 1.5m and equidistant from the center of the plank. Cousin Throckmorton wants to stand on the right-hand end of the plank. If the plank is to remain at rest, how massive can Throckmorton...
  28. E

    What potential reference for a cylinder inside a cylinder

    The question is A long metal cylinder with radius a is supported on an insulating stand on the axis of a long, hollow, metal tube with radius b. The positive charge per unit length on the inner cylinder is λ, and there is an equal negative charge per unit length on the outer cylinder...
  29. F

    My past manager probably doesn't like me I need a reference

    I'm a STEM major, college sophomore, looking for an internship this summer and a place I'm applying to needs 3 references, after I finished my interviewed there. I tried contacting my manager from my intern position last year asking if she'd be a reference. Problem is she didn't respond after a...
  30. I

    The Paradox of Inertial Frames: Exploring the Limits of Classical Physics

    I'm reviewing physics after ~30yrs of neglect, starting with Halliday & Resnick (and the internet). Here's what I understand to be standard Newtonian/classical inertial frames: 1. There exists a set of reference frames, called inertial frames, in which mass, time, force, acceleration, etc. are...
  31. J

    How to determine speed with no frame of reference?

    You are standing on one. The two planets were closing in on a speed of 1x. You just accelerated one of the 2 planets towards the other with a super powerful rocket engine, and then sat on one of them. Now they are closing in on each other at speed 10x. The universe is otherwhise empty. The...
  32. H

    Relative Motion & Rotation of Axes of Reference

    I'm still very early on in my reading, so forgive me if this question isn't coherent. In the "historical introduction" section of the 1920 University of Calcutta translation of the original papers of Einstein and Minkowski available via the MIT online archive, mention is made of the fact that...
  33. N

    Classical Elaborate reference on Wave motion

    Dear experts, I need to study wave motion in detail. Mainly mechanical waves on a string, reflection of mechanical waves, standing waves, resonance etc. I am looking for a book which covers these basic concepts in minute detail. For example , I believe that the phase shifts during wave...
  34. S

    Analysis Reference book for "Fredholm integral equations"

    Hi, I am looking for a good reference book for "Fredholm integral equations". + a book with lots of examples related to this topic! Thanks for your help.
  35. throneoo

    Definition of inertial reference frames

    What is the definition of an inertial frame ? I've read that Inertial frames are reference frames in which Newton's first law applies (i.e.bodies subject to zero net external force moves at constant velocity) , however Newton's 1st law itself is only valid under inertial frames. I find it weird...
  36. Soumalya

    Prob/Stats References to Probability & Statistics for Engineers

    I am looking for an introductory reference to the subjects 'Probability and Statistics' intended to be used for self study.By an introductory reference I mean an undergraduate level text that would teach me the subjects from the very basic to an advanced level.I wish to focus primarily on...
  37. Amaterasu21

    Question about rotating reference frames

    Hello, I have a few questions about rotation and relative motion. Suppose we transport the proverbial spinning ice skater used to demonstrate conservation of angular momentum to beginning physics students to a universe with only her and two planets. She is now spinning in deep space...
  38. MagnetDude

    Engineering Textbook for electormechanical design reference

    I am working on a lot of things with electric motors, and many other electromechanical devices. Any textbook comes to mind?
  39. M

    Time Difference between two inertial frames of reference

    Homework Statement Let S and S' be two inertial frames of reference where S' is moving at a velocity of 0.6c relative to S. When x = x' = 0, t = t' = 0, where t and t' are time of the clocks on S and S' respectively and x and x' are the x-coordinates of the S and S' frames respectively. An...
  40. AdityaDev

    Frame of reference and Pseudo forces

    If you have a car and a pendulum is hanged inside it, and if you watch from outside the car,and if the car has some acceleration, then you see the bob moving in opposite direction of motion of car. For a person standing outside, he knows that the car has some acceleration. What causes the bob...
  41. A

    Classical Need a reference for Mechanics book

    I need a reference book to read the following topics- a) Generalized coordinates; b) D'Alembert's principle and Lagrange's equations; c)Hamilton equations; d) Motion of rigid bodies in two dimensions. The topics need to be covered only at graduation level. Thanking you in anticipation.
  42. PWiz

    Is a Zero Frame of Reference Possible in the Universe?

    Alright so I'm still trying to get a hang of the theories of relativity, and this thing has really been bugging me. All forms of motion (and sometimes even physical observations) are defined for a particular local frame of reference. But is there any "stationary" frame of reference in the...
  43. K

    Inertial frame of reference question for stacked boxes

    Hello, I was wondering about a question and how it would be reconciled within Newton's laws of motion. Take a case where two boxes are stacked on top of each other, and the bottom box rests on a frictionless surface. Now, imagine a rope is attached to the top box, and tension is applied to...
  44. DiracPool

    Relativity Musings: Gravitation, Acceleration & Inertial Ref Frames

    I have a 3-pack of related relativity musings I was hoping someone(s) could enlighten me on: 1) Since the reach of gravity is infinite and the universe is homogeneous and isotropic with regards to the distribution of matter, is it fair to say that no object, even those in deep interstellar or...
  45. AdityaDev

    Electrochemistry: reference electrode

    Reduction half reaction : Cu2++2e- -> Cu(s) I have a doubt in using the reference electrode. For example if I have the calomel electrode (ESCE=0.24V) how do I use it with the copper half cell? Are these reactions correct? Cu2++2e- -> Cu(s) 2Hg+2Cl -> Hg2Cl2+2e- To get Ecell=0.24+ECu|Cu2+
  46. Hercuflea

    Emailing a postdoc offerer for future reference?

    Would it be acceptable to look at post-doc offers (as a pre-PhD student) and email the offerer to ask whether they would accept a PhD in X field? If a post-doc says it requires you to have a PhD in a "closely related field", would it be alright to email them and ask if you do a PhD in something...
  47. mrnike992

    Speed of Light: What Frame of Reference?

    My apologies for the numerous times this has probably been posted, but I wasn't able to find a great answer through the search tool alone. Please correct me on anything I state incorrectly, and direct me to the answer.. My question is, if the speed of light is 299,792,458 m/s, its speed is...
  48. W

    Worship, Reference Points & Time: A Story of an Old Lady

    Last Tuesday ,I came across an old lady[looking a bit disorientated] in the street who asked me "Is today a Sunday ,I need to go to church?" I said to her "Its a Tuesday" This set me thinking about "phases of the moon","364.25 days for Earth to orbit Sun", 52 weeks made up of 7 days etc etc...
  49. M

    Light angles measured in a moving reference frame

    I've managed to get through all of this question without trouble until part d). The full question is given here: I've calculated the "true" angles of Star A and Star B as 71.57 degrees and 45 degrees respectively in Frame S, and the "light" angles should be the same, since the stars are...
  50. T

    ADC/DAC Sample Rate and Reference Voltage

    I am currently working on a circuit design that is featuring both a ADC and DAC. I'll focus my question on the ADC in this thread. I'm trying to figure out what each pin does. Am I correct in assuming that the Vref pin on the an ADC chip is used as the maximum encoded value for a voltage? Say...
Back
Top