Definition of Scalar And Vector Quantities - SS1 Physics Lesson Note

Scalar and vector quantities are terms used to describe different types of physical quantities based on their properties and characteristics. 

1. Scalar Quantity: A scalar quantity is a physical quantity that has only magnitude (size or numerical value) but does not have a specific direction associated with it. Scalar quantities can be fully described by a single real number or value. Examples of scalar quantities include mass, temperature, time, speed, distance, energy, and volume. Scalar quantities can be added, subtracted, multiplied, and divided using ordinary arithmetic operations.

2. Vector Quantity: A vector quantity is a physical quantity that has both magnitude and direction. In addition to the numerical value or magnitude, vectors also have a specific direction in space. Vectors are usually represented by arrows, where the length of the arrow represents the magnitude, and the direction of the arrow represents the direction of the vector. Examples of vector quantities include displacement, velocity, acceleration, force, momentum, and electric field. Vectors cannot be simply added or subtracted using regular arithmetic but require vector addition or subtraction, taking into account both magnitude and direction.

In summary, scalar quantities have magnitude but no direction, while vector quantities have both magnitude and direction. Scalars are described using a single numerical value, while vectors require both magnitude and direction to fully describe them. Understanding the distinction between scalars and vectors is crucial in physics as it affects the mathematical treatment and interpretation of physical quantities and their behaviour in various phenomena and calculations.