Edexcel IGCSE Maths 复习笔记 5.1.4 Vectors - Modulus

Edexcel IGCSE Maths 复习笔记 5.1.4 Vectors - Modulus

What is a vector?



  • Vectors have various uses in mathematics
    • In mechanics vectors represent velocity, acceleration and forces
    • At IGCSE vectors are used in geometry – eg. translation
    • Ensure you are familiar with the Revision Notes Vectors – Basics


  • Vectors have magnitude and direction
    • These notes look at finding the magnitude, or modulus, of a vector
    • Vectors are given in column vector form




What is the magnitude or modulus of a vector? 



  • This depends on the use of the vector
    • For velocity, magnitude would be speed
    • For a force, magnitude would be the strength of the force (in Newtons)


  • The words magnitude and modulus mean the same thing with vectors
  • In geometry magnitude and modulus mean the distance of the vector
    • This is always a positive value
    • The direction of the vector is irrelevant


  • Magnitude or modulus is indicated by vertical lines
    • |a| would mean the magnitude of vector a





How do I find the magnitude or modulus of a vector

  • Pythagoras’ Theorem!



Exam Tip

Sketch a vector to help, it does not have to be to scale – you can then use this to form a right-angled triangle.

Worked Example