Overview
This lecture explains the differences between scalar and vector quantities in physics, including their definitions, examples, and how vectors can be represented visually.
Scalar Quantities
- Scalars are physical quantities that have only magnitude (size) and no direction.
- Magnitude is the numerical value or amount of a quantity.
- Examples of scalars include speed, distance, mass, temperature, and time.
- Speed is scalar because it does not specify direction, only how fast an object moves.
Vector Quantities
- Vectors are physical quantities that have both magnitude and direction.
- Examples of vectors include velocity, displacement, acceleration, force, and momentum.
- Displacement is a vector because it describes both how far and in what direction an object moves.
- Velocity differs from speed by including direction.
Visual Representation of Vectors
- Vectors are represented by arrows; length shows magnitude, and arrow points in the direction.
- For example, a 4 km north vector is a long arrow pointing up, while 2 km west is a shorter arrow pointing left.
- Negative vectors can indicate the opposite direction (e.g., –2 km east is equal to 2 km west).
Key Terms & Definitions
- Magnitude — the size or numerical value of a quantity.
- Scalar — a quantity with magnitude but no direction.
- Vector — a quantity with both magnitude and direction.
- Displacement — the straight-line distance from start to finish in a specific direction (vector).
- Speed — how fast something moves regardless of direction (scalar).
- Velocity — speed with a specified direction (vector).
Action Items / Next Steps
- Review each example of scalars and vectors.
- Watch upcoming videos for details on velocity, displacement, acceleration, force, and momentum.