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. Z

    What is the mathematical concept behind the shear in gravitational lensing?

    Hello all, Sorry about the crappy title. I'm actually not sure what the call the thing I'm here to ask about, which is why I'm here. In the process of reading about gravitational lensing, I've run across an odd mathematical thing that I just don't know how to handle. When a spherical...
  2. E

    Conservation of Angular Momentum and Vectors

    Hi there, I'll come straight out with this, I'm really struggling to understand the conservation of angular momentum. A common example involves someone sitting on a rotating chair holding a rotating wheel. If the wheel is held so that the axis of rotation is vertical then the person...
  3. J

    Help with Vectors: Calculating Displacement, Speed & Velocity

    Homework Statement Hi everyone, my problem is this: Darryl drives his load of tomatoes 14.0 km [E], 6.0 km [N], 12.0 km [ N 15° E], and then 2.0 km [N 65° E]. This takes him 42 minutes. a) Calculate Darryl's distance and displacement. Draw a diagram and show your work. b) Calculate...
  4. F

    Orthogonal space-like vectors.

    Hey, I read that if a four-vector is 'four-orthogonal' to a time-like four vector then it must be space-like. I showed this quite easily. I also read that a space-like vector can be orthogonal to another space-like vector, but can't seem to prove it. I wondered if someone could help me.
  5. samjohnny

    Free body diagram and force vectors

    Homework Statement Attached, where AC=BC=2R and CD=CE=3R. I need to work out the force the cylinder exerts on the cross section (in order to work out the moment at C). So first I'm trying to work out the free body diagrams for this system. Is it as I've attached? How do I draw the tension...
  6. C

    Are left-invariant fields mapped onto the manifold Killing vectors?

    Left invariant fields on a group G satisfies a lie algebra; say we have an n-dimensional Lie algebra for which the fields ##{X_1, \ldots , X_n}## is a basis. Let these satisfy the algebra ##[X_a, X_b] = c_{ab}^c X_c##. Suppose now that we have a Riemannian manifold with killing vectors...
  7. JasonHathaway

    Proof for Vectors Product: (A×B) . (B×A) + (A . B)^2 = A^2 . B^2"

    Homework Statement Proof that (A×B) . (B×A) + (A . B)^2= A^2 . B^2 Homework Equations A×(B×C)=(A . C)B - (A . B)C The Attempt at a Solution Assuming K=(A×B) K . (B×A) + (A . B)^2 = A^2 . B^2 B . (A×K) + (A . B)^2 = A^2 . B^2 B . [A×(A×B)] + (A . B)^2 = A^2 . B^2 B . [(A . B)A...
  8. N

    Proving Perpendicularity: Solving Vectors Question | Homework Help

    Homework Statement If two linearly independent vectors are of equal magnitude, prove that their sum is perpendicular to their difference. Homework Equations v1.v2 = 0 The Attempt at a Solution This question doesn't seem that hard but it's really confused me. Help is appreciated...
  9. JasonHathaway

    Proving the Mixed Product Formula for Vectors in R3

    Homework Statement Prove that (A×B) . [(B×C)×(C×A)]=(A,B,C)^2 where A, B, C are vectors in R3. Homework Equations W×(U×V)=(W . V) U - (W × U) V The Attempt at a Solution Assuming K=(A×B), M=(B×C): K . [M×(C×A)] K . [(M . A) C - (M . C) A] [(M . A)(K . C) - (M . C)(K . A)]...
  10. adjacent

    Proving Parallel Vectors: AB & CD

    Homework Statement This is not a homework question,but I will post here anyway. ##\vec{AB}=\left(\begin{matrix} 1 \\ 2 \end{matrix}\right)## ##\vec{CD}=\left(\begin{matrix} 2 \\ 4 \end{matrix}\right)## (a)Prove that ##|\vec{CD}|## is double of ##|\vec{AB}|## (b)Prove that ##\vec{CD}## is...
  11. M

    Determining quantities as vectors or not

    Why are some quantities vectors while others aren't? For example, we can calculate both current and current density, but why do we only consider current density to be a vector and current a scalar quantity? Is it a purely arbitrary convention or is it something more mathematically fundamental? I...
  12. B

    Parallel Vectors - Learn How to Calculate

    Sorry - Answered my own question.
  13. E

    2-dimension polar basis vectors

    I'd like to understand why i cannot seem to be able to define unit polar basis vectors. Let me explain: We have our usual polar coordinates relation to Cartesian: x = r cosθ ; y = r sinθ if I define \hat{e_{r}}, \hat{e_{\vartheta}} as the polar basis vectors, then they should be...
  14. N

    Find Values of a and b for Perpendicular Vectors

    Homework Statement If \underline{v} = a\underline{i} + 2\underline{j} + 3\underline{k} and \underline{w} = 2\underline{i} +b\underline{j} - \underline{k} and |\underline{v}| = |\underline{w}|, find the values of a and b so that \underline{v} and \underline{w} are perpendicular. If v =...
  15. A

    Cross products for unit vectors in other coordinate systems

    I am a bit confused often when I have to compute cross products in other coordinate systems (non-Cartesian), I can't seem to find any tables for cross products such as "phi X rho." in spherical I think that these unit vectors are considered to be "perpendicular," so would phi X rho just be "+/-...
  16. C

    Finding Angle Between Two Vectors Using Inner Products

    Hi all, I am having trouble understanding inner products. Specifically, using inner products to find the angle between two vectors. Our lecturer has given an example, as follows; (u,v)= 4u1v1 + u1v2 + u2v1 + u2v2, where u=(1,0) v=(0,1) (u,v)=|u|.|v|cosθ 1=(√4)cosθ θ=∏/3 Surely the...
  17. Quarlep

    Differences between row and column vectors

    I want to show a vector in matrix but I didnt uderstand differentes between row matrix and column matrix Let's suppose I have a 2i+3j How I will show this vector in matrix ? I will use a row matrix or column matrix.
  18. H

    Component method for vectors

    Homework Statement Use the componant method to determine the total displacement given by the two vectors shown in each diagram. Homework Equations The Attempt at a Solution I thought I just had to find the third unknown side, and use the pythagorean theorem, but I was...
  19. Y

    Vectors Help -- Weight hanging from a cord

    Homework Statement A cord 7m long has its ends tied to a horizontal board 5m apart. A weight of 50 N is suspended from a ring so that the weight is free to slide along the cord in a vertical plane. A horizontal force pulls the ring to a position such that the cords on either side of the ring...
  20. Y

    Finding the Tension of a Guy Wire Supporting a 100ft Tower

    1. Given info ( with attached photo) The guy wire supporting a 100ft tower has a tension of 550lbs. Use the distance shown in the figure write the component form of the vector F representing the tension of the wire. 2. My attempt at the solution My first assumption was to make a vector using...
  21. 7

    Regarding r and sign convention for Position vectors for moments

    Homework Statement The Attempt at a Solution I'm having trouble understanding how r1 = -1.5j and r2= r3 = 0. Can anyone make this a little clearer for me? I've spent quite a while trying to wrap my head around it but to no avail.
  22. J

    Calculating Solid Angle Between Three Vectors: A Scientific Guide

    How I do for calculate the solid angle formed by 3 vectors like: http://s30.postimg.org/61lpvmi4h/solid.jpg ?
  23. JasonHathaway

    Understanding Unit Vectors: A Step-by-Step Guide

    Hi everyone, Just want to know how does the the unit vector become in that form: \vec{n}=\frac{2x\vec{i}+2y\vec{j}}{\sqrt{(2x)^{2}+(2y)^{2}}}=\frac{x \vec{i}+y \vec{j}}{4}
  24. R

    Facing problem in a questions on Vectors

    If |vector a+vector b|= |vector a- vector b| show that vector a is perpendicular to vector b. A friend of mine suggested me to square both the sides of the equation. At the end, the result was vector a. vector b=0, from which it could be proved that the vectors are perpendicular. But...
  25. E

    Derivation of Phi-Hat wrt Phi in Spherical Unit Vectors

    Homework Statement I just want to know how to get from this: ∂ø^/∂ø = -x^cosø - y^sinø to this: = -(r^sinθ+θ^cosθ) Homework Equations All the equations found here in the Spherical Coordinates section: http://en.wikipedia.org/wiki/Unit_vector The Attempt at a Solution I've...
  26. M

    Set of vectors, linearly dependent or independent?

    Homework Statement Check if the following set of vectors are linearly dependent or independent: A) V1= \stackrel{1}{1} V2= \stackrel{1}{3} B) V1= \stackrel{\stackrel{1}{2}}{3} V2= \stackrel{\stackrel{2}{1}}{3} C) V1= \stackrel{1}{3} V2= \stackrel{2}{1} V3= \stackrel{-1}{2} Homework...
  27. esis

    MHB Difference Between Lines and Vectors (Linear Combination Problem)

    Hello Everyone! I am working my way through Gilbert Strang's book on linear algebra. I came across a set of solutions to the problems whose solutions are not listed in the book http://www.scribd.com/doc/86849289/1/Problem-Set-1-1-page-8. However, as I was working on the following question: I...
  28. T

    Representing Vectors in 3D Space

    Homework Statement In 3D space a full vector can be represented I. All the following except A. In Cartesian vector form B.As a magnitude times a unit vector C. As a Cartesian vector times a unit vector D. As magnitude with coordinate angles Homework Equations The Attempt at a...
  29. T

    Coordinate angles of three dimensional vectors

    Homework Statement If u know the value of two coordinate angles there is an ulimeted amount of possibility for finding the third coordinate angle A. True B. False Homework Equations The Attempt at a Solution I .not too sure about this one any suggestions would be appreciated I...
  30. S

    MHB These two problems are based on Vectors, dot product and distance for sphere.

    Problem 1: Let S1 be a sphere centered at(0, 1, -3) with radius 1 and let S2 be a sphere centered at (3, 5, -9) with radius 2. Find the distance between the two spheres. problem 2: Given three non-zero vectors v1, v2, v3 we say that they are mutually orthogonal when v1 dot v2= 0, v1 dot v3=0 ...
  31. K

    Vectors - velocity is changing but speed is not

    Vectors -- velocity is changing but speed is not... Homework Statement Which pair of vectors represent an object whose velocity is changing but whose speed is NOT changing? Homework Equations The Attempt at a Solution E? V is going left, indicating negative, while acceleration...
  32. ThomasMagnus

    Confusion over angle between vectors

    Homework Statement I have been doing dot and cross product recently. I get how to calculate everything; however, I am confused about which angle to use when asked to find the angle between two vectors. When you use the cross product, you always end up with 2 answers, for example 120° and...
  33. T

    What Is the Dot Product of Two Parallel Unit Vectors?

    Homework Statement The dot product for two.parralel pointing.unit.vectors is ? A. 1 B. 0 C. -1 D. Undefined [b]2. Relevant equation The Attempt at a Solutionsince they are unit vectors they have a magnitude of 1,this implies that the dot product is 1,since the angle between...
  34. T

    Find the True Statement About Dot Product of Two Vectors

    Homework Statement The dot product of.two vectors is -1which of the following statements is true A. They must be unit vectors pointing in opposite directions. B. They must be unit vectors pointing j. The same direction. C. They must be more than 90( and less than 270 )degrees from each...
  35. R

    Solve for Vector Intersections: r=<t,t2,-3t> & 2x-y+z=-2 | Check My Work

    Homework Statement Please check my work for the following problem: Find the point(s) where the curve r = <t,t2,-3t> intersects the plane 2x-y+z=-2. 2. The attempt at a solution t + t2 -3t = -2 (t-2)(t+0) = -2 t=0 and t=-2 plugging those values in yields: r(0) =...
  36. D

    How many unknowns are there in 2-D space?

    Homework Statement In 2-D space, the maximum number of unknown information is... Select one: a. 4 b. 2 c. 3 d. 1 e. 0 Homework Equations The Attempt at a Solution i think the answer is 1 comments would be appreciated
  37. Y

    MHB Which of the Following is Incorrect Regarding Matrices and Vectors?

    One last question on these topics, I need to choose the WRONG statement, and they all seem correct to me... a) If A is a squared matrix for which \[A^{2}-A=0\] then A=0 or A=i b) If A and B are diagonal matrices, then Ab=BA c) A 4X4 matrix with eigenvalues 1,0,-1,2 is "diagonlizable" d) The...
  38. Q

    Geometric Methods for Adding Vectors: Are You Doing It Right?

    Represent the below vector relationship geometrically, illustrating two different ways of adding vectors. Vector a - vector b = vector c. I know the above relationship can also be expressed as: Vector a + (-vector b) = vector c. In other words, we flip the direction of vector b and add as...
  39. B

    Understanding Linear Combinations of Vectors

    Hello Everyone, Pardon me if the following is incoherent. From what I understood of what my professor said, he was basically saying that when a vector can be written as a linear combination of some vectors in a span, this means, geometrically, that the vector is in the plane that the span of...
  40. K

    Contravariant and Covariant Vectors

    I remember I have read somewhere that contravariant/covariant vectors correspond to polar/axial vectors in physics, respectively. Examples for polar/axial vectors are position, velocity,... and angular momentum, torque,..., respectively. Is this right? Can I prove that, say, any axial...
  41. S

    Primitive Translation Vectors

    Homework Statement The vectors r1 and r2 below represent atomic positions in a crystal. r1 = (n1 + n3)ax + (n2 + n3)ay + n3az r2 = (n1 + n3 + 1/2)ax + (n2 + n3 1/2)ay + (n3 + 1/2)az Assume first that the two vectors above correspond to two different types of atom. Find a set of...
  42. T

    Are Killing Vectors the Key to Solving Complex Equations?

    See below. I screwed up the edit and the use of tex.
  43. Z

    Proving Linear Independence of vectors

    Homework Statement Let x1 = (1, 2, -1, 1), x2 = (-1, -1, -1, -1), x3 = (1, 1, 1, 0), x4 = (-2, -1 -4 -1) Show that x1, x3 and x4 are linearly independent Homework Equations The Attempt at a Solution Now I used the equation: ax1+bx2+cx3+dx4=0 Hence forth the augmented...
  44. jdawg

    What's the Difference Between Ax and i-Hat in Vector Notation?

    Homework Statement So this isn't really a specific homework question, it's more of a general one. What is the difference between ax and i(hat)? I thought they were the same thing. Can someone please explain the difference? Homework Equations The Attempt at a Solution
  45. PsychonautQQ

    Identifying BBravais Lattice with vectors Given

    Homework Statement Given that the primitive basis vectors of a lattice area (a/2)(I+J),(a/2)(j+k), (a/2)(k+i), where I j and k are the usual three unit vectors along Cartesian coordinates, what is the bravais lattice? Homework Equations The Attempt at a Solution So just drawing...
  46. jdawg

    Calculate 2C*(3AxB) for Vectors A, B, and C

    Homework Statement For the following three vectors, what is 2C*(3AxB) A=3i+3j-4k B=-3i+2j+3k C=-6i-8j **All of the capital letters are vectors** Homework Equations The Attempt at a Solution 2A=2(3i+3j-4k) =6i+6j-8k 2AxB=(6i+6j-8k)*(-3i+2j+3k)...
  47. P

    Null Killing Vector & Conserved Quantity - Physics Forums

    If space-like Killing vectors are associated with a conserved momentum, and timelike Killing vectors are associated with a conserved energy, what is the conserved quantity associated with a null Killing vector? For instance, "v" in ingoing Eddington Finklestein coordinates...
  48. Saitama

    MHB Find Vectors $\vec{v_1}$, $\vec{v_2}$, $\vec{v_3}$ Given Dot Products

    Problem: Find $\vec{v_1}$,$\vec{v_2}$ and $\vec{v_3}$ given that: $$\vec{v_1}\cdot \vec{v_1}=4$$ $$\vec{v_1}\cdot \vec{v_2}=-2$$ $$\vec{v_1}\cdot \vec{v_3}=6$$ $$\vec{v_2}\cdot \vec{v_2}=2$$ $$\vec{v_2}\cdot \vec{v_3}=-5$$ $$\vec{v_3}\cdot \vec{v_3}=29$$ Attempt: Assuming the vector...
  49. F

    MHB Why Can't Vectors be Divided? - Exploring the Math Behind the Answer

    I was reading my computer graphics textbook and under frequently asked questions one was "why is there no vector division?" and it said "it turns out there is no 'nice' way to divide vectors". That's not a very good explanation. Why is it that matrices can't be divided?
  50. M

    Electric Field Vectors: Does Force Follow Direction?

    Is the electric force on a charged particle always in the same direction of the field? What if it is an uncharged particle? If you have an electron, with the field vectors pointing radially inward, then place a proton in the field, then yes since the proton is attracted towards the electron...
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