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.

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  1. F

    ASTM A572: Temperature Effects on Yield

    Does anyone happen to know of a good reference for ASTM A572 (any grade) that lists temperature effects on yield? The standard only lists room temperature specs. Thanks
  2. D

    Simple Harmonic Motion Reference Circle

    Homework Statement Through simple harmonic motion produced on a trampoline Ivan ossilates freely, with a period of 0.85s. On a reference circle show Ivans position after 1/8th of a cycle. Label (and solve) the distance of this position from the equilibrium position.(Max displacement is...
  3. D

    Transforming angular distributions between different reference frames

    My problem is related to the Brookhaven experiment of the J/psi discovery and the Y discovery at Fermilab (in both cases, protons over a Berillium fixed target). In both cases they had a resonance decaying into two leptons, and the detecting system consisted of two arms, covering a relatively...
  4. S

    Reference Letters for Co-op/Internship | 3rd Year Engineering Student

    Hi, I am currently a 3rd year electrical engineering student and I will looking for 12-16 month co-op/internship following the completion of this year. I have received some reference letters from my professors and just wanted to know, is it advisable to include one or two along with my resume...
  5. B

    Does kinetic energy vary by frame of reference?

    Kinetic energy is 1/2mv^2, and velocity varies depending on velocity of the observer, so does kinetic energy also vary depending on the velocity of the observer? for example, someone sitting in a bus who slides a 2 kg brick down the center isle of the bus at 5 m/s could say the has a kinetic...
  6. K

    Newton's Laws and Inertial Reference Frames

    does an object with constant acceleration follow Newton's laws? with constant velocity? a stationary object? i think the last two are true, but I'm confused whether a constant acceleration (m/s/s) of whatever still applies to an inertial frame or is a noninertial frame? because in a sample...
  7. C

    What is the Semimajor Axis of a Planet's Orbit in Different Reference Frames?

    Homework Statement There is a planet of mass m_1 orbiting a star of mass m_2. One question is "What is the semimajor axis of the planet's orbit in the coordinate system centered at the star's center", and another is "What is the semimajor axis of the planet's orbit centered at the center of...
  8. H

    Reference frames for photon collisions (pair production)

    Homework Statement Hi, My question probably has a simple answer, but I've been scratching my head over it a little too long so I thought I would ask it here. I have three initial photons involved in a collision with 4-momenta k1, k2 and k3. I have two reference frames: frame 1: the...
  9. H

    Reference frames for photon collisions

    Hi, My question probably has a simple answer, but I've been scratching my head over it a little too long so I thought I would ask it here. I have three initial photons involved in a collision with 4-momenta k1, k2 and k3. I have two reference frames: frame 1: the centre of mass frame of...
  10. D

    Velocity is Relative: Reference Frames

    1. The Question Verbatim "A pilot starting from Athens, New York, wishes to fly to Sparta, New York, which is 320 km from Athens in the direction 20.0 N of E (LETS CALL THIS VECTOR = A). The pilot heads directly for Sparta and flies at an airspeed of 160km/h. After flying 2.0 h, the pilot...
  11. P

    This seemingly-easy reference problem is making me crazy

    This seemingly-easy reference problem is making me crazy! The airport terminal has a moving sidewalk to speed passengers through a long corridor. Larry does not use the moving sidewalk. He takes 145 s to walk through the corridor. Curly, who simply stands on the moving sidewalk, covers the same...
  12. V

    Time gap between explosions in moving frame of reference

    Came across the following interesting problem : Two explosions take place at the same place in a rest frame with a time separation of 10 s in that frame. A) Find the time between explosions, as measured in a frame moving with a speed 0.9 c with respect to the rest frame according to...
  13. A

    Determine which reference frame is inertial

    Suppose an empty space and two points. The distance from point A to B is d = k . t^2 k=constant t = time The question is: Which point is an Inertial Frame of reference ? Suppose an empty space and two references frames. A is rotating at w with center B. But B is...
  14. O

    Titled reference frame, N2L with position and velocity

    A ball is thrown with initial speed vo up an inclined plane. The plane is inclined at an angle(fi) above the horizontal, and the ball's initial vecity is at an angle (theta) above the plane. Choose the axes with x measured up the slope, y normal to the slope and z across it. Write down Newton's...
  15. O

    How Do Moving Frames Affect the Observation of a Puck's Path?

    I am standing (yes, the question actually goes like this!) on a level floor at the origin of an inertial frame S and kick a frictionless puck due north across the floor. a.) Write down the x and y coordinates of the puck as functions of time as seen from my inertial frame. (use x and y axes...
  16. B

    Why is the time interval between the events in frame S larger than in frame S'?

    Homework Statement Two events happen at the same point x'(0) in frame S' at t(1)' and t(2)' a) Use equations x=gamma*(x'+vt') and t=gamma*(t'+vx'/c^2) to show in frame S the time interval between the events is greater than t(2)'-t(1)' by a factor of gamma Homework Equations The...
  17. A

    What is an inertial frame of reference ?

    what is an inertial frame of reference ? Simple ?
  18. F

    Moving Reference Frames and elastic collision

    Homework Statement Consider a head-on, elastic collision between two bodies whose masses are m and M, with m << M. It is well known that if m has speed v0 and M is initially at rest, m will bounce straight back with its speed unchanged, while M will remain at rest (to an excellent...
  19. F

    Moving Reference Frames and Cannon

    This is the question: A physics lecture demonstration uses a small canon mounted on a cart that moves at constant velocity v across the floor. At what angle theta should the cannon point (measured from the horizontal floor of the cart) if the cannonball is to land back in the mouth of the...
  20. A

    Magnetic field, frames of reference

    In the link: that I found here 5 minutes ago ( thanks for the link ) there are two drawings: the first and the second. In the first the link explains that there is a magnetic field, because the - charges are moving. In the second the link explains that there is not a magnetic field...
  21. H

    Time dilation on accelerated reference frames

    Hey all, I made a post earlier today on gravitational time dilation. It got me thinking that in any accelerated frame of reference there must also be a time dilation, due to the equivalence principle. This can simply be a elevator accelerating through space or it can be caused by centripetal...
  22. H

    Max error without reference junction

    Hi I'm using thermocuple as a temp. sensor, it is inside soldering handle output is 0 mV (tested with digital voltmeter at range 200 mV) at room temperature. I'll amplify that voltage using AD623 I cannot use Ice bath to set ref. junction at 0 deg C. I thought using table (ref junction at 0 deg...
  23. T

    Velocity Calculation: Marilyn Bell's Lake Ontario Crossing Anniversary Swim

    In an anniversary celebration of Marilyn Bell's 1954 crossing of Lake Ontario a swimmer set out from the shores of New York and maintained a velocity of 4m/s [N]. As the swimmer approached the Ontario shore, she encountered a cross current of 2m/s [E 25deg S]. Find her velocity with respect to...
  24. M

    What Forces Influence the Moon in the Sun's Inertial Frame of Reference?

    What forces affect on the Moon in the Inertial frame of reference which is the Sun? +gravity form the Sun +gravity from the Earth +centrifugal force from the rotationary movement of the Moon round the Earth is this list correct?
  25. N

    Fluid Dynamics standard reference

    Hi. What's a standard reference for physicsts concerning the topic of fluid dynamics or computational FD.
  26. M

    Frame of Reference- arrow traveling through a tube

    I was just wondering about the following problem. Suppose that you have an arrow placed in a tube. If the arrow travels at a relativistic speed, does there exist a frame of reference such that the arrow is completely in the tube with extra tube at its ends? Does there exist a frame of...
  27. L

    Possible webpage title: Defining Inertial Reference Frames in Classical Physics

    Hello, Every definition of an inertial reference frame that I have read stated that it is a frame in reference in which Newton's laws are valid. But is it possible to define it in this way: it is a coordinate system that is not accelerating relative to some absolute reference point. Is there...
  28. N

    Fixing "Undefined Reference" Error in .o File

    I'm trying to call a function from a .o file, and it keeps telling me: "undefined reference to ..." where the ... is whatever function I'm trying to call. Do any of you have any idea what's wrong with this?
  29. R

    Why Does an Object Far Away Seem Slow?

    Why does an object far away looks like it's going very slow when it's going really fast? And then the object seems really fast when it's near me. I just started driving and I always try to find an answer but really can't. Thanks :)
  30. W

    Kinetic Energy in reference frame

    One way to attack a satellite in Earth orbit is to launch a swarm of pellets in the same orbit but in the opposite direction. Suppose a satellite in a circular orbit 500km above Earth's surface colides with a pellet having a mass of 4g. What is the KE of the pellet in the reference frame of...
  31. E

    Mathematica Mathematical Reference: Overview of Fields & Formulations

    Hi I am searching for some kind of mathematical "reference". My math knowledge is mainly from a five year technical school and some basic university courses. I can solve equations (linear and differential), use vectors and matrices, use geometry in 2/3 D, use probability and statistics...
  32. gabee

    Magnetism: which reference frame?

    A friend and I have been discussing what we think is an error in our textbook (either that or a misunderstanding on our part). The book gives an example in which two protons are initially traveling parallel to one another in the same direction with equal velocity. We think that since the...
  33. K

    Inertial and Non-Inertial Frames of Reference Question

    Homework Statement A rubber stopper of mass 25g is suspended by string from a handrail of a subway car traveling directly eastward. As the subway train nears a station, it begins to slow down, causing the stopper and string to hang at an angle of 13 degrees from the vertical. What is the...
  34. L

    Does Weight Change with Reference Frame? A Question Explored

    Sorry for the trivial (and certainly already covered) question. Does a body's weight change with the ref. frame? If I had a very long scale on which the body can move without friction, would I observe the scale to sign different values according if I am stationary with the scale or with the object?
  35. S

    Newton's Second Law in NON-inertial frame of reference

    Homework Statement The steel ball is suspended from the accelerating frame by the two cords A and B. The angles (they are on the inside) are both 60 degrees. Determine the acceleration of the frame which will cause the tension in A to be twice that in B. The acceleration is going to the...
  36. K

    Is the intellect the absolute reference frame?

    Hi I know that the following can never be done in the real world, but in theory, if the vectors of all particles, antiparticles, photons etc. in the universe could be summed, would that qualify as an absolute reference frame for that instant in time? Clearly each instant would have a...
  37. K

    Help, Need a reference web site

    Hi I'm in the middle of writing up the Frank-Hertz experiment as part of my lab module this year, but I'm having trouble finding a 'reliable' website that I can use to quote the electron energy value (ie 4.9eV). I'm afraid my lecturer refuses to acknowledge wikipedia as a good source...
  38. P

    Best comprehensive Reference Book for Pure Math?

    For those of you who don't know, "Formulas and Theorems" is basically a compilation of thousands of math theorems, 6000+ formulas, with a summary of their proofs, covering most of what was known in the late 18th century. What I'm looking for is a comprehensive reference book with worked...
  39. K

    Does light truly have no reference frame?

    I've seen several responses (and links) to the question "What happens when something is traveling at the speed of light" and understand that the answer is twofold. First no object can travel that fast because it would require an infinite amount of energy to acelerate physical objects to that...
  40. J

    Inertial Frames of Reference: Examining Forces & Acceleration

    so here r ma doubts => it is sometimes heard tat inertial frame of referance is only an ideal concept and no such inertial frame exists.comment. =>the accelaration of a particle is zero as measured from an inertial frame of referance . can we conclude tat no force acts on it? => a...
  41. Ivan Seeking

    PLC Brands Popular in China: A Reference Guide

    Does anyone know or have a reference indicating what PLC [programmable logic controller] brands are popular in China?
  42. G

    Can the Order of Events Change in Different Frames of Reference?

    Suppose event A causes event B. To one observer, event A comes before event B. Is it possible that in another frame of reference event B could come before event A? If so, how?
  43. K

    Proper frame of reference and the formation of black holes

    Since in our proper frame of reference the fall of material into a black hole would appear to take for an eternity, would it not follow then that all black holes would appear as these instead? Would in fact all black holes appear this way? What if you have a small black hole and then have...
  44. matthyaouw

    How Should You Cite Revisors in a Revised Book Edition?

    I'm having trouble writing out a reference for a book. My normal format is: Author (year of publication) Title publisher, place of publication eg: Trueman, A.E. (1949) Geology and scenery in England and Wales. Penguin Books, Harmondsworth This book is a revised edition, revised without help...
  45. U

    Is Speed Real and Who Has the Correct Frame of Reference in the Universe?

    Our planet is moving through our solar system and our solar system is moving through our galaxy and our galaxy is moving within the local group and are local group is moving through our universe, so how fast are we moving right now, and if i then jump into my spaceship and accelerate am i...
  46. A

    Reference angles always positive?

    Simple question. Are reference angles always positive??
  47. N

    Discover Top Reference Books for Studying the Sun | Nitya's Book Recommendations

    Hi, Is there any book that can be read as an alternative to the 'Cambridge Encyclopedia of the Sun'? I have not been able to buy the above but wanted to know if there are any other books that might have the same information. Thanks Nitya
  48. E

    What forces must be considered in non-inertial rotating reference frames?

    dealing with non-inertial rotating reference frames, real forces such as the centripetal force need to be taken into account,or only the forces that can be really observed within the frame? because from the perspective of the rotating frame, objects should be at rest. it only appears logical...
  49. A

    Inertial Reference Frames- circular?

    My textbook basically defines an inertial reference frame as follows: If you have an object O that has no forces acting on it, and there is a reference frame R where the acceleration of O with respect to R is zero, then R is a inertial reference frame. This to me seems circular. How does one...
  50. T

    What is the acceleration of a sliding box in a decelerating truck?

    :uhh: First, I will state the problem - A hauling truck is traveling on a level road. The driver suddenly applies the brakes, causing the truck to decelerate by an amount (g/2). This causes a box in the rear of the truck to slide forward. If the coefficent of sliding friction...
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