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. JD_PM

    A Orthogonal spacelike and timelike vectors and inertial frames

    I know that any vector ##V## in Minkowski spacetime can be classified in three different categories based on its norm ##|V| = \sqrt{V \cdot V} = V^{\mu}V_{\mu}##. These are: 1) If ##V^{\mu}V_{\mu} < 0##, ##V^{\mu}## is timelike. 2) If ##V^{\mu}V_{\mu} > 0##, ##V^{\mu}## is spacelike. 3) If...
  2. A

    I Gradient Vectors: Perpendicular to Level Curves

    The gradient transforms a scalar function into a vector function where the vector components are the rates of change of the functions with respect to its independent variables. Also, the properties of the gradient are: It lies in the plane. It is perpendicular to the level curves and points...
  3. E

    B Sign problems with vectors, how can we "resolve" this....

    There are a few details, either convention or understanding, that I was hoping someone could help to clarify. Consider the object below, acted upon by a few forces including an unknown ##\vec{N}##, which I have split into its horizontal and vertical components ##\vec{N_{x}}## and...
  4. S

    I Principal difference between complex numbers and 2D vectors revisited

    I know this topic was raised many times at numerous forums and I read some of these discussions. However, I did not manage to find an answer for the following principal question. I gather one deals with the same set in both cases equipped it with two different structures (it is obvious if one...
  5. M

    MHB Are the vectors linearly independent?

    Hey! :o We have that the vectrs $\vec{v},\vec{w}, \vec{u}$ are linearly independent. I want to check if the pairs $\vec{v}, \vec{v}+\vec{w}$ $\vec{v}+\vec{u}$, $\vec{w}+\vec{u}$ $\vec{v}+\vec{w}$, $\vec{v}-\vec{w}$ are linearly indeendent or not. Since $\vec{v}, \vec{w}, \vec{u}$...
  6. P

    Finding the angle between vectors a and m, knowing the magnitude of m and n

    Summary: Finding angle between vectors a and m, knowing magnitude of m and n, also the angle between m and n with 60 degrees. Using geometry, it looks like the angle is 30 degrees but the answer is suppose to be 54.7 degrees. I'm not sure how to solve this.
  7. J

    Translational and rotational velocity

    For a cylinder rolling down an inclined plane, does the tangential velocity of a point a distance R from the axis of rotation equal the velocity of the center of mass?
  8. G

    MHB Rewriting vectors in different coordinates

    Lets say you have a vector in spherical coordinates; how do you rewrite this vector into a cartesian one and vice versa? Im fine with rewriting coordinates but vectors have got me confused. I've tried digging through info online but I couldn't find any good examples. In the following task...
  9. O

    Teaching Forces - Having issues with directions & vectors

    Hi everyone. I'm the only physics teacher at my school, so I have nobody to bounce ideas off of. I'm having a problem with students getting confused with direction when calculating net force. I teach an introductory physics course. It's the first time the students have ever seen physics and...
  10. T

    Help With Understanding Resultant Forces By Connecting Vectors

    Hi all I am trying to get my head around resultant forces. I am happy that if I have a vector diagram with 2 forces I can work out graphically the resultant forces by connecting the head of one of the vectors to the tail of the second vector. The confusion comes in when I have 3 or more...
  11. O

    What's the use of unit vectors?

    Homework Statement: Hallo. Can somebody explain to me what's the importance-use of unit vector in the below (second) equation? Why isn't the first equation just enough to describe r? What's the reason for unit vector to even exist? Homework Equations: in the photos
  12. n3pix

    Converting Velocity Formula: Polar to Cartesian

    I have a little question about converting Velocity formula that is derived as, ##\vec{V}=\frac{d\vec{r}}{dt}=\frac{dx}{dt}\hat{x}+\frac{dy}{dt}\hat{y}+\frac{dz}{dt}\hat{z}## in Cartesian Coordinate Systems ##(x, y, z)##. I want to convert this into Polar Coordinate System ##(r, \theta)##...
  13. Alexandra Fabiello

    Confusion in Adding Vectors: How to Find Missing Magnitudes and Angles?

    I am admittedly entirely confused as to where to start, sorry. This is the diagram I'm given that fits with the rA + rB. If rB is 47.0 degrees above the x-axis normally, it would be the same counter-clockwise here, right? Then 180 - 47 = 133 degrees for the clockwise angle. But now I'm stuck...
  14. astroman707

    I Solve Vector Equation: iy + jx & (i + j)/√2

    I'm reading div grad curl for my math methods class, and I came across this question: "Using arrows of the proper magnitude and direction, sketch each of the following vector functions: (a) iy + jx, (b) (i + j)/√2 I don't understand the notation. Why is there an y and x next to the i and j in...
  15. KF33

    B How do I differentiate vectors with derivatives and properties?

    Homework Statement: The homework problem is included below, but I am looking at the derivatives of vectors. Homework Equations: I have the properties of derivatives below, but not sure they help me here...
  16. nomadreid

    I Quantum states: only vectors?

    Elementary question: Is there ever a case where the solutions for a wave equation turn out not to be a vector (in Hilbert space of infinite complex-valued dimensions, or a restriction to a subspace thereof) , but something else -- say, (higher-order) tensors or bivectors, or some such? My...
  17. F

    I Transforming Vectors and Tensors

    Hello, I was pondering on the following: a vector is a specific entity whose existence is independent of the coordinate system used to describe it. To start, I guess I need to state that we are describing the vector from the same reference frame using different coordinate systems (Cartesian...
  18. A

    MHB Proving parallel lines using points and vectors

    Hey, this is a problem given to me by my prof for an assignment, and the TAs at my tutorials haven't been much help. Was wondering where to go with this question. Also, I'm a uni freshman who isn't used to the whole concept of proofs, and a lot of what my profs say seem to be a slew of...
  19. Pencilvester

    I Lie derivative of hypersurface basis vectors along geodesic congruence

    Hello PF, here’s the setup: we have a geodesic congruence (not necessarily hypersurface orthogonal), and two sets of coordinates. One set, ##x^\alpha##, is just any arbitrary set of coordinates. The other set, ##(\tau,y^a)##, is defined such that ##\tau## labels each hypersurface (and...
  20. Joshua G

    Trying to find two vectors with known sum, what am I doing wrong?

    v_1 = <-8/21,-20/21> v_2 = <50/21,-20/21> When I take the dot product of v_2 and <2,5> I get zero, indicating they are perpendicular. Sorry for the hand writing.
  21. P

    Stuck on a few Vector homework problems

    I'm stuck on a few Vector homework problems. I don't quite understand how to write vectors A+B and A-B for questions 1b and 2b. I tried starting with calculating the magnitude for vector A+B on question 1b and then followed by finding theta, but I'm not sure if that's what I'm supposed to do...
  22. Like Tony Stark

    Decomposing velocity vectors into polar axis

    Well, I drew the polar and standard axis centered in the particle and wrote which angles were equal to 60° so I could decompose the velocity. The problem says "moves towards it (the radar) with velocity v=5 m/s, so that's one of the components. But I realized that the velocity "cuts" the angle...
  23. S

    I How do you derive those basis vectors in GR?

    You may be familiar with how you can express a vector field as a linear combination of basis vectors like so: X = Xi∂i Now, I know that normally, the basis vectors ∂i can be derived by taking the derivatives of the position vector for the coordinate system with respect to all the axes like...
  24. christang_1023

    Can Algebraic Calculations Alone Determine Vector Set Constraints Accurately?

    1. I consider this problem algebraically, ##c\cdot \vec{u}+(1-c)\cdot \vec{v}=c(1,2)+(1-c)(2,1)=(c,2c)+(2-2c,1-c)=(2-c,1+c)##; since the constraint I know is ##c\geq 0##, I can conclude the expected vectors##(x,y)## must have ##x\leq2, y\geq 1##. 2. Similarly, I get...
  25. S

    I Applying the spacetime interval to regular vectors instead of curves

    I have some questions. Let us assume for these questions that I am using the (- + + +) sign convention. Firstly, we know that if you have a parameterized curve ξ(s), then you can find the proper time between two events at points s1 and s2 by using this formula (assuming that the curve is...
  26. michael872940

    Can I determine mass & spring k from graph of wave, t, a, & vectors?

    Classical problems for hookes law generally give either mass or spring constant. What if I have a graph of a wavelike structure that is oscillating which I can use to measure for example: T (period), t (time), Δx (displacement), v (velocity), a (acceleration) and other variables is this...
  27. J

    Forces and vectors: pulling a baby buggy on soft ground

    I don't know exactly where to start with this problem. But I'm going to try this, cos θ= adj/hyp cos 40° = Fx/100 Fx=100 cos 40° =76.60= 77N??
  28. torito_verdejo

    Advantages of Polar Coordinate System & Rotating Unit Vectors

    What is the advantage of using a polar coordinate system with rotating unit vectors? Kleppner's and Kolenkow's An Introduction to Mechanics states that base vectors ##\mathbf{ \hat{r}}## and ##\mathbf{\hat{\theta}}## have a variable direction, such that for a Cartesian coordinates system's base...
  29. hilbert2

    I Notation for vectors in tensor product space

    Suppose I have a system of two (possibly interacting) spins of 1/2. Then the state of each separate spin can be written as a ##\mathbb{C}^2## vector, and the spin operators are made from Pauli matrices, for instance the matrices ##\sigma_z \otimes \hat{1}## and ##\hat{1} \otimes \sigma_z##...
  30. SchroedingersLion

    A Exploring the Discreteness of Allowed k Vectors in Crystals

    Greetings, I am having troubles with understanding the allowed k vectors in a crystal. Bloch's theorem gives us discrete energy bands for each wave vector k. However, only discrete k vectors are allowed. Using periodic boundary conditions, the discreteness is easy to show. But I am having a...
  31. A

    Vectors and car displacement

    I have drawn a arrow pointing straight down (South) 110km and an arrow off that to the right(west) 70km.I know that the distance of the journey would be 180km. How do I go about finding the displacement?
  32. karush

    MHB 10.2 Determine if the set of vectors form a vector space

    Determine if the set of vectors $\begin{bmatrix} x\\y\\5 \end{bmatrix}\in \Bbb{R}^3$ form a vector space ok if I follow the book example I think this is what is done $\begin{bmatrix} x_1\\y_2\\5 \end{bmatrix} +\begin{bmatrix} x_2\\y_2\\5 \end{bmatrix} +\begin{bmatrix} x_2\\y_2\\5...
  33. T

    Are vectors independent of reference frames?

    Ok, this is the notation I am going to use in this thread: uppercase means vectors, while "[V]c" means coordinates of vector V in frame c. I'm reading from a book: i have a reference frame "a" and a reference frame "b" rotated with respect to "a", the vector connecting the frames origin is R. We...
  34. M

    B Precision Representation of Vectors Using a Spiral on a Sphere

    Source: https://mathinsight.org/vectors_cartesian_coordinates_2d_3d "A vector in three-dimensional space. A representation of a vector a=(a1,a2,a3)a=(a1,a2,a3) in the three-dimensional Cartesian coordinate system." My question is does representation of a vector to arbitrary precision require 3...
  35. lwin

    Vectors Homework Help: Find Degree

    Can’t seems to find the degree
  36. B

    Momentum vectors graph ( from aqa paper)

    If i were to take one point as my origin and draw the two momentum, one for the initial collestion and one going from the wall after, from the origin point, then drawing horizontally i would get the answer as B as the resultant? Should i assume that for any resultant vector the direction can...
  37. M

    I Why is there a contradiction?

    Let: ##\nabla## denote dell operator with respect to field coordinate (origin) ##\nabla'## denote dell operator with respect to source coordinates The electric field at origin due to an electric dipole distribution in volume ##V## having boundary ##S## is: \begin{align} \int_V...
  38. M

    I Solving 2 equations and 2 unknowns with vectors

    Hi, I have a work-related problem to solve and I'm not sure where to start and a pointer would be appreciated. I have the following two sets of polar equations V1 + V2 = Vx V1 + V2 + V3 = Vy, where Vx, V3, and Vy have been measured with reasonable accuracy, maybe +/-2% Any thoughts on how to...
  39. E

    Vectors & Angles Problem Analysis

    Hello, it is my first post here and I am not really sure whether this is the right section. I did not have the chance to take a look at the rules of the forum but I will as soon as I can (I feel a bit guilty for that, I'm sorry...). This is not "homework", I am just studying the amazing L&L...
  40. SueJ

    How do I show that 2 moving objects collide?

    They collide when their positions are the same, so I plugged the information for the boat into equation 1 to get an expression for d which is (2i, +j)t^2 Then I used equation 4 to get an expression for d for the branch, which is (-4i, +j)t I would need to take into account the different...
  41. M

    Magnetic field "lines" confused with magnetic field "vectors"

    I might be a slow learner, but am still trying to understand the difference between field lines and vectors. I've got that magnetic field lines are symbolic and that the directional arrows applied (from north to south) are a convention. But see the attached image. The field lines form a closed...
  42. T

    Relative Velocity of Swimmer: How to Calculate Total Time for Different Paths?

    So I was just wondering if someone could check my method for (b) as sometimes I can have a tendency of getting the relative components wrong ect. Diagram 1 (a) Time for PY: ##T=L/c## Time for YP: ##T=L/c## Total Time:##2L/c## (b) Velocity for PY: ##c-v##...
  43. Dhaneshragu

    Find the incorrect relation from the figure

    I tried making B vector in direction of D vector with a minus sign and after doing so I got the answer C vector - D vector= -A vector. But it's given as incorrect. I don't know why. Please explain how other options are correct.
  44. opus

    I Looking for deductions to find the angle between vectors

    I have a question in my text (Intro Mechanics by Kleppner) and a question is to find the cosine and sine between two vectors. It gives me the cosine piece: $$\cos(\vec A, \vec B) = \frac{\vec A ⋅\vec B}{|A||B|}$$ which I assume is just from the dot product, but it has no derivation of this, and...
  45. pixel

    I How Do Dual Vectors Differ From Regular Vectors in Physics?

    I've been looking at various online sources for relativity and have some confusion about "dual vectors." I'm hoping for some very basic information/examples from physics, not abstract mathematical concepts from the field of vector spaces. 1. In addition to the vector/dual vector distinction...
  46. C

    I need some clarification for a high school vectors question (accelerating bird)

    Homework Statement A bird flying in the air accelerates 2.82 m/s2 north for 4.11 seconds. the final velocity of the bird is 9.09 m/s [east]. What was the initial velocity of the bird? Homework Equations vf=v0+a*t v(average)=(v0+vf)/2 v=d/t d=v0t +½at2 tanθ=opp/adj The Attempt at a Solution...
  47. P

    I Confusion about index notation and operations of GR

    Hello, I am an undergrad currently trying to understand General Relativity. I am reading Sean Carroll's Spacetime and Geometry and I understand the physics (to a certain degree) but I am having trouble understanding the notation used as well as the ideas for tensors, dual vectors and the...
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