What is a Vector?
A vector is a mathematical entity that has both magnitude (size) and direction. Unlike scalar quantities that only have magnitude (like temperature or mass), vectors provide additional directional information. Vectors are typically represented graphically by arrows, where the length of the arrow indicates the magnitude and the arrowhead points in the direction.
Notation
Vectors are often denoted by boldface letters (e.g., v) or with an arrow above the letter (e.g., (\vec{v})). In component form, a vector in two-dimensional space can be represented as (\vec{v} = \langle v_x, v_y \rangle), where (v_x) and (v_y) are the components along the x and y axes, respectively.
Common examples of vector quantities include:
- Velocity
- Force
- Acceleration
- Displacement
- Electric field
Properties and Operations
Vector Operations
Addition and Subtraction
Vectors can be added or subtracted using two methods:
- Geometric method (tip-to-tail)
- Component method (adding/subtracting corresponding components)
For example, if (\vec{a} = \langle a_x, a_y \rangle) and (\vec{b} = \langle b_x, b_y \rangle), then:
- Addition: (\vec{a} + \vec{b} = \langle a_x + b_x, a_y + b_y \rangle)
- Subtraction: (\vec{a} - \vec{b} = \langle a_x - b_x, a_y - b_y \rangle)
Scalar Multiplication
When a vector is multiplied by a scalar (regular number), the result has:
- Changed magnitude (by the scalar factor)
- Same direction (if scalar is positive)
- Opposite direction (if scalar is negative)
Vector Components
Any vector can be broken down into components along coordinate axes. For a 2D vector:
x_component = magnitude × cos(θ)
y_component = magnitude × sin(θ)
Dot Product
The dot product (or scalar product) of two vectors results in a scalar:
a·b = |a||b|cos(θ)
Cross Product
For 3D vectors, the cross product produces a vector perpendicular to both input vectors:
| Operation | Result |
|---|---|
| i × j | k |
| j × k | i |
| k × i | j |
Applications
Physics
"Physics without vectors is like poetry without words." - Anonymous Physicist
Vectors are essential in physics for:
- Motion and forces
- Electromagnetic fields
- Quantum mechanics wave functions
- Momentum and angular momentum
Engineering
Engineers use vectors for:
- Structural analysis
- Fluid dynamics
- Electrical circuit analysis
- Robot kinematics
Computer Graphics
In computer graphics and game development, vectors are used for:
- Character movement
- Camera positioning
- Collision detection
- Particle systems
Learn more about vectors in computer graphics at OpenGL Documentation
Navigation
Modern GPS systems use vectors to:
- Calculate distances
- Determine directions
- Plan optimal routes
- Track movement
Learn more about GPS technology at GPS.gov
Programming with Vectors
Many programming languages provide vector implementations:
# Python example using NumPy import numpy as np vector1 = np.array([1, 2, 3]) vector2 = np.array([4, 5, 6]) dot_product = np.dot(vector1, vector2)
For Python vector operations, check out NumPy Documentation
For further learning, consider exploring resources like Khan Academy's Vector Mathematics or MIT's OpenCourseWare on Linear Algebra.