Overview
This lecture explains the difference between scalar and vector quantities, using everyday examples to highlight how each is defined and expressed.
Scalar Quantities
- Scalar quantities are fully described by a number (magnitude) and a unit of measurement.
- Examples of scalar quantities include temperature (e.g., 25°C), mass (e.g., 1 kg), and energy.
- No direction or orientation is needed to specify a scalar quantity.
Vector Quantities
- Vector quantities require three components: magnitude (how much), direction (line or axis), and sense (which way along the direction).
- Examples include displacement (e.g., 5 meters northeast), velocity, and force.
- Giving only the magnitude (e.g., 5 meters) is insufficient; the direction and sense must also be specified.
- When moving an object (like a crate), specifying up/down, right/left, and the amount moved is necessary to define the action as a vector.
Key Terms & Definitions
- Scalar Quantity — a physical quantity that is completely specified by its magnitude and unit of measurement.
- Vector Quantity — a physical quantity that is fully defined by its magnitude, direction, and sense.
Action Items / Next Steps
- Review examples of scalar and vector quantities from your textbook.
- Practice identifying whether given quantities are scalars or vectors.