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Scalars and Vectors

Motion, forces and energy · IGCSE Physics

Scalars and Vectors — IGCSE Physics Notes

Exam years: 2025–2027 Topic: Motion, forces and energy Lesson 2 of 48

Scalars and Vectors

A scalar quantity has magnitude only. Examples: distance, speed, time, mass, energy, temperature.

A vector quantity has both magnitude and direction. Examples: force, weight, velocity, acceleration, momentum, electric field strength, gravitational field strength.

Key Formula

For perpendicular vectors: Resultant (R) = √(X² + Y²)

Example — Addition of Forces

Step-by-step
  • 15 N East and 10 N North → perpendicular vectors.
  • R = √(15² + 10²) = √325 ≈ 18 N, direction: North-East.

Graphical Representation

Use the head-to-tail method and scale diagrams.

Common Mistake

Forgetting to include direction when writing a vector result.