What is Vectors: Definition and 1000 Discussions

In mathematics, physics and engineering, a Euclidean vector or simply a vector (sometimes called a geometric vector or spatial vector) is a geometric object that has magnitude (or length) and direction. Vectors can be added to other vectors according to vector algebra. A Euclidean vector is frequently represented by a ray (a directed line segment), or graphically as an arrow connecting an initial point A with a terminal point B, and denoted by






A
B






{\displaystyle {\overrightarrow {AB}}}
.A vector is what is needed to "carry" the point A to the point B; the Latin word vector means "carrier". It was first used by 18th century astronomers investigating planetary revolution around the Sun. The magnitude of the vector is the distance between the two points, and the direction refers to the direction of displacement from A to B. Many algebraic operations on real numbers such as addition, subtraction, multiplication, and negation have close analogues for vectors, operations which obey the familiar algebraic laws of commutativity, associativity, and distributivity. These operations and associated laws qualify Euclidean vectors as an example of the more generalized concept of vectors defined simply as elements of a vector space.
Vectors play an important role in physics: the velocity and acceleration of a moving object and the forces acting on it can all be described with vectors. Many other physical quantities can be usefully thought of as vectors. Although most of them do not represent distances (except, for example, position or displacement), their magnitude and direction can still be represented by the length and direction of an arrow. The mathematical representation of a physical vector depends on the coordinate system used to describe it. Other vector-like objects that describe physical quantities and transform in a similar way under changes of the coordinate system include pseudovectors and tensors.

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  1. A

    Proof of product rule for gradients

    Can someone please help me prove this product rule? I'm not accustomed to seeing the del operator used on a dot product. My understanding tells me that a dot product produces a scalar and I'm tempted to evaluate the left hand side as scalar 0 but the rule says it yields a vector. I'm very confused
  2. F

    Semantics question about vectors

    Hi all. I have a question that is more about definitions or language, rather than physics. So (Euclidean) vectors used in Physics are "geometrical entities endowed with a magnitude and a direction". At least this is what i find if I look up "vector" in english speaking websites. My "problem"...
  3. S

    Contravariant and covariant vectors

    I know if the number of coordinates are same in both the old and new frame then A.B=A`.B` . But if the number of coordinates are not same in both old and new frame then A.B=0 means that both the vectors A and B are perpendicular. Why is it so that if the number of coordinates of both the frames...
  4. sunrah

    General vectors and tangent space

    Given a scalar function g defined on a manifold and a curve f:λ -> xa, the change of the function along the curve is \frac{dg}{d\lambda} = \frac{dg}{dx^{a}}\frac{dx^{a}}{d\lambda} = T^{a}\frac{dg}{dx^{a}} where \frac{dx^{a}}{d\lambda} = T^{a} is the tangent to the curve. The argument that I...
  5. tomdodd4598

    Can the Dot Product of Four Vectors Maintain Positive Component Signs?

    Hi there, I understand that taking the dot product of two four vectors automatically applies the metric tensor to the second vector. Is there a way to take write the dot product, using vector notation, in a way which keeps the signs of all of the components positive? Thanks in advance.
  6. B

    Flux Vectors of One E-: Force Vectors or Scalar Quantity?

    How many magnetic/electric flux vector one e- can produce? Only one or many? (Here I mean flux as force vectors and not a scalar quantity like in flux density.)
  7. Z

    Are photons really anti-correlated off their basis vectors?

    The wiki page https://en.wikipedia.org/wiki/Bell's theorem states the following which I agree with: Suppose the two particles are perfectly anti-correlated—in the sense that whenever both measured in the same direction, one gets identically opposite outcomes, when both measured in opposite...
  8. B

    Proving a set of vectors is linearly independent

    Hey all, student100's brother here, he got me to create an account to ask my question here... I'm taking an introduction to linear algebra class and we had a test problem to prove a set of vectors is linear independent: ##V = v_1, \dots, v_n \in \Bbb R^n## such that each element of the set is...
  9. C

    How to prove if 3 arbitrary vectors are coplanar

    Homework Statement Let s and t be scalars. show that u, v and su + tv are coplanar. u and v are arbitrary vectors, Homework EquationsThe Attempt at a Solution Well, i suppose if they are coplanar, triple scalar product of them should be 0, right? and su+tv is evidently a linear combination of...
  10. Erkan Tur

    Position Vectors: Get Help & Understand Concepts

    Homework Statement Homework Equations Relevant equations can be derived from the formulas, by exchanging x to v, v to a, etc. The Attempt at a Solution I've tried to graph them, but I am not able to visualize or understand them. Please help me about these questions, I need some hints. If...
  11. J

    Adding velocity vectors to get average velocity

    If you're driving in a car and map out all the displacement vectors, you can add the segments to get the total displacement. Correct? Why can't we add the various velocity vectors for the different segments to get the average velocity. ? Could you add up all the velocity vectors and divide by...
  12. N

    Difficulty understanding vector transformation law

    I am having a hard time understanding vector transformations. I know that vectors must transform a certain way and that dual vectors (or covectors) transform the "opposite" way. What is strange to me is that the basis vectors transform like dual vectors and the basis dual vectors transform like...
  13. Q

    Linear independence of 5 dimensional vectors in R^3

    i am asked to determine whether 3 vectors which have 5 dimensions (x,y,z,w,u) are linearly dependent or independent in R^3. it doesn't make any sense. should i ignore w and u dimensions and take x,y,z only? because if i dont, all answers would be same, doesn't matter in r^3 or R^4 etc. the...
  14. olgerm

    Tensor in D-dimensional space crosswise with 2 vectors

    I have 2 vectors ##\vec {V}=(v_1,v_2,v_3,v_4...v_D)## and ##\vec {X}=(x_1,x_2,x_3,x_4...x_D)## in D-dimensional euclidean space. I want a tensor ,which is crosswise with both of them. I think that the tensor is parallel with (D-2)-dimensional area, am I right? I do not know a lot about tensors...
  15. G

    Trouble finding direction of two force vectors

    Homework Statement [/B] A block of mass 2kg is accelerated by the two forces F1 = 8i + 3j and F2 = -5i - 7j, (a) What is the net force on the block in unit vector notation, and what is its magnitude and direction? (b) What is the magnitude and direction of the acceleration?Homework Equations...
  16. Issy04

    Resolving forces in equilibrium on inclined plane

    Homework Statement Solve for the forces P and N acting on an object in equilibrium on an inclined plane. Weight=10N, angle is 30 degrees http://blob:https%3A//www.physicsforums.com/d431a152-5681-411b-ba57-809320539165 Homework Equations Trigonometry, i.e. sin, cos, tan rules. The 'Z' rule...
  17. kostoglotov

    Graphing Eigenvectors and Sine Curves: Understanding the Relationship

    In my text, it tells me to find the eigenvectors of a 2nd difference matrix and graph the eigenvectors to see how they fall onto sine curves. imgur link: http://i.imgur.com/oxbkTn6.jpg My question is simple but general. What does this even mean? How did they produce this graph from the...
  18. R

    Calculate force in north/east directions given 2 components

    Hello, My question is about using vector components to find a force in a particular direction. I already have the answer, I just don't understand it and would like an explanation if anyone has one. If I have two vectors with radial velocities (in this case it's measurements of ocean current...
  19. E

    Vectors Q: Solving OR & OP | Homework Forum

    NOTE: Thread was moved to Homework forums and thus has no homework template... I managed to find (a) but i couldn't figure out (b). I think OR = OP + PR = (2/3)a + t( (-1/15)a + (2/5)b) but i don't know how to go further please guide or help me with this please. Thanks
  20. G

    Help determining force vectors?

    I'm tossing around an idea in my head, but I'm outside of my knowledge base. A guitar string is suspended between two points (nut and a bridge) and tightened to a certain tension. I assume most of the stress is in line with the strings, but force can do funny, counterintuitive things. I want...
  21. N

    How does rotation have vectors?

    In my textbook they used the right hand rule to show that rotation has vectors instead of just being positive or negative relative to its direction of rotation of a vinyl record. In the image the record was going clock wise so by the right hand rule it was going downward which makes sense, but...
  22. vetgirl1990

    Why Use Unit Vectors in Calculations?

    I'm confused about what situations you should use unit vectors in... and it seems that when I approach the same problem using unit vectors vs. without unit vectors, I get different answers. Why? To illustrate my confusion, here's an example that I tried solving using unit vectors, and without...
  23. C

    Finding force vectors of gravity along a curve

    hello. I'm looking for some general guidance as to which methods to use where. i'm wanting to find the force vectors on an object as it moves along a general curve in a space (imagine a roller coaster). for example the parametric curve. z=t x=cos(t) y=sin(t)I know i need to find the partial...
  24. Einstein's Cat

    Learning Quantum Mechanics with Dirac: Understanding Ket Vectors

    I'm attempting to learn the mathematics of quantum mechanics using textbooks such as "The Principles of Quantum Mechanics" by Dirac. I'm uncertain however of how ket vectors work! Say |A> + |B> = |C>, then what does |C> please represent?
  25. B

    Describe all vectors orthogonal to col(A) with a twist

    I am trying to solve the following problem: Let A be a real mxn matrix. Describe the set of all vectors in F^m orthogonal to Col(A). Here, F^m could be C^m. Now in the real case, I'd say that the column space of A is the row space of A^T, and it is well known that the row space of a matrix is...
  26. L

    Finding distance for a given value between vectors

    Homework Statement Let u = (2,k,1,-4) and v = (3,-1,6,-3) For which values of k is the distance d(u,v) = 6? Homework EquationsThe Attempt at a Solution 6 = √((3-2)2 + (-1-k)2 + (6-1)2 + (-3-4)2) 6 = √(1 + 1 + k2 + 25 + 21) 6 = √(k2 + 48) 36 = k2 + 48 k = √-12 The answers seem to be 6k, -16k...
  27. R

    Another i j k vectors question.

    Hi everyone. Aftrer doing a search I found loads of information but I still can't get my head around these damm vectors. I understand the basics and how to work out the dot product if given the question in a given way. An example of the questions I am being asked are: The following two...
  28. Driverfury

    Angle between two vectors (Only by having their lengths)

    Homework Statement Ok guys, I'm studying Physics and I started, of course, by learning about vectors. So I have this problem: There are two vectors: A (its length is 3 m) and B (its length is 4 m). I have not other informations about them. I want to know how I can dispose them to get a vector...
  29. M

    I want to find the vector components of an MRI pixel -- How?

    I have a Dicom Image that is interpreted as an array. Each cell is a pixel. Each pixel has a value. I want to find the vector components (x,y,z) of a pixel. Specifically, I want to find magnetic field vectors for each pixel. The image is for H1 atoms. Freq = 297, B0 = 3. How would you do this...
  30. C

    Add Vectors: 55km South + 34km North

    Homework Statement Illustrate the addition of the following two vectors and calculate the resulting vector: 55km [South] + 34km [North]. Homework EquationsThe Attempt at a Solution [/B] The attempt at the solution is below. What is troubling me is the overlap of the vectors and how to draw...
  31. W

    Solve Truss Joints Using Method of Joints

    Homework Statement Determine the axial forces in the members of the truss and indicate whether they are in tension or compression. Homework Equations Fx = 0 Fy = 0 Mp = 0 The Attempt at a Solution I attempted to find the reactions at the supports first. So: Fx = 0 = Bx + 800cos(250)N Fy...
  32. M

    Dimension of the span of a set of vectors

    My linear algebra is a bit rusty. Let ##A=\{\bar{v}_1, \dots, \bar{v}_1\}## be a set of vectors in ##R^n##. Can dim(span##(A))=n## without spanning ##R^n##? I guess I'm unclear on how to interpret the dimension of the span of a set of vectors.
  33. W

    How Do You Calculate the Reactions at Supports in a 3D Equilibrium Problem?

    Homework Statement The 1.1m bar is supported by a ball and socket support at A and 2 smooth walls. The tension in the vertical cable CD is 1kN. Draw the Free Body Diagram of the Bar. Determine the Reactions at A and B. Homework Equations Equillibrium equations. Perhaps the vector...
  34. R

    Physics: Multiplying Unit vectors

    [Moderator note: Post moved from New Member Introductions forum, so no template] I am having trouble understanding how to multiply unit vectors. I know that: (please excuse the notation) i^×j^ = k^ j^×k^ = i^ k^×i^ = j^ The question I am stuck on is: What is (i^×j^)×k^? So far I have (i^×j^)...
  35. I

    Satellite Position: Calculating ECI from ECEF

    Homework Statement Hi! I just found this forum after trying to calculate something regarding a satellite's orbit. Hope that you can help me here. So, I need to calculate the matrix of a satellite's site vectors. I have found it in the ECEF form, but since the satellite is doing observations in...
  36. R

    Draw vectors for a car being dragged along a ramp

    Homework Statement A 1070-kg car is held in place by a light cable on a very smooth (frictionless) ramp, as shown in the figure(Figure 1) . The cable makes an angle of 31.0 ∘above the surface of the ramp, and the ramp itself rises at 25.0 ∘ above the horizontal. [/B] http://imgur.com/gkOQuRq...
  37. JulienB

    Determine components of a vector without knowing the angle

    Homework Statement (I roughly translate the problem statement from German) Given the vectors a = (1,-2,3) and b = (1,1,1), divide the vector a in two components a1 (parallel to b) and a2 (perpendicular to b). Homework Equations In a previous question of the problem, I found that: a.b = 2 a x...
  38. K

    Axial & Polar Vectors: List & Examples

    Can you list as many axial vectors and polar vectors as possible?
  39. S

    Why work done by a force is a scalar product

    Why work done by a force was taken as dot product between force applied and displacement caused?
  40. P

    How are the direction of primitive vectors determined in BCC crystal structures?

    hello i have browsed this forum for topics about this, and i found them very enlightening and helped a lot in terms of finding the length of the primitive vectors , the problem that i have is with the direction of said primitive vectors , while in fcc they are more or less easy to visualize in...
  41. askhetan

    Matrix Elements as images of basis vectors

    I'm trying to understand the maths of QM from Shankar's book - Principles of Quantum Mechanics: On page 21 of that book, there is a general derivation that if we have a relation: |v'> = Ω|v> Where Ω is a operator on |v> transfroming it into |v'>, then the matrix entries of the operator can be...
  42. sunrah

    Basis vectors of Minkowski space

    Hi, I'm doing a first course in GR and have just found out that \eta_{ab} = g(\vec{e}_{a}, \vec{e}_{b}) = \vec{e}_{a} \cdot \vec{e}_{b} where g is a tensor, here taking the basis vectors of the space as arguments. I haven't seen this written explicitly anywhere but does this mean that...
  43. D

    SR & Lorentz Scalar Fields: Covariant Diff. & Wave Amplitude

    Hi. In GR , covariant differentiation is used because the basis vectors are not constant. But , what about in SR ? If the basis vectors are not Cartesian then they are not constant. Does covariant differentiation exist in SR ? And are for example spherical polar basis vectors which are not...
  44. Mr Davis 97

    Defining Vectors: Scalars vs 1-Dimensional Vectors

    A very informal definition of a vector could be that it is a tuple of ordered numbers. As such we use the symbol ##\mathbb{R}^n## to refer to the set of vectors with real numbers and n many components. ##\mathbb{R}^2## refers to an element such as ##\vec{a} = (x, y)##. And ##\mathbb{R}^3##...
  45. W

    What is the angle between coupled forces with a given moment and magnitude?

    Homework Statement The moment of the couple is 600k (N-m). What is the angle A? F = 100N located at (5,0)m and pointed in the positive x and positive y direction -F = 100N located at (0,4)m and pointed in the negative x and negative y direction Homework Equations M = rxF M = DThe Attempt at a...
  46. D

    Need help finding the difference of two forces

    Homework Statement Find P-Q (P=11.5 kN, Q=12.5kN) Homework Equations x-component = cos(angle)*force y-component = sin(angle)*force Pythagorean Theorem (to find resultant magnitude): c2 = a2 + b2 arctan (y-component / x-component) : to find angle of resultant The Attempt at a Solution The...
  47. P

    Find minimum value for coefficient of static friction

    Homework Statement Homework Equations Newton's 2nd Law The Attempt at a Solution I was wondering if anyone could verify that I have all the correct vectors or if I am missing any. I just wanted to check before I started trying to derive the equations. [/B]
  48. R

    How Many Basis Vectors in Hilbert Space?

    What is the dimensionality, N, of the Hilbert space (i.e., how many basis vectors does it need)? To be honest I am entirely lost on this question. I've heard of Hilbert space being both finite and infinite so I'm not sure as to a solid answer for this question. Does the Hilbert space need 4...
  49. I

    Need help finding magnitude of A - B + C given 3 vectors

    You are given three vectors. A = 46.0 at θ1 = 56.6° above the +x axis B = 25.0 at θ2 = 34.4° above the −x axis C = 32.0 along the −y axis.Determine A - B + C (magnitude and angle from the positive x axis). Determine the angle relative to the positive x-axis, positive above and negative belowI...
  50. M

    Help illustrating magnetic field line vectors and gradients

    Magnetic field lines around multipolar magnets get quite complex. There are local field vectors and field gradients in the x, y, & z plane. In the following diagrams I have tried to illustrate field lines around a centrally (half and half) charged disc magnet. The top diagram represents the...
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