Class 9 Unit 1: Measurement Measurement and it's importance: The process of comparing unknown physical quantity with a known standard quantity is called measurement. The importance of measurement are as follows: It is essential in trade i.e. selling, buying and exchanging of goods. It is required in performing daily life activities. Measurement of medicine is a must for the proper treatment of diseases. It is essential for scientific experiments while collecting data and information. Measurement plays an important role in the manufacturing of goods such as clothes, food items Watch this video : fundamental and derived quantities Unit and its types: A unit is defined as a convention to define an amount of physical property in a specific system of units. Units are of two types: Fundamental units Derived units Fundamental units: The units of the fundamental quantities are called fundamental unit. Those units which are independent cannot be derived from other unit is called fundament...