Concise Selina Solutions for Class 8 Physics Chapter 2 Physical Quantities and Measurement

Physical Quantities and Measurement, deal with a detailed explanation of the different types of physical quantities and their measurements. Physical quantity is the property of an object that can be quantified. For instance, the physical quantities are the length of a rod or the mass of a body. Measurement is the act of comparing a physical quantity with its unit. Measurement result is the value of a physical quantity obtained by means of measurement. Density is defined as its mass per unit volume. It is, essentially, a measurement of how tightly matter is crammed together.

Density is the fundamental property of a matter. Every object has a different density. Densities of various materials vary based on the factor of how closely the molecules are packed. The molecules are densely packed in substances having high density. A body encounters two types of forces at being immersed in a liquid, the weight of its own and the counteracting buoyant force respectively. The chapter also briefs about the relation between S.I. and C.G.S units. Law of Floatation: The weight of the solid floating in a fluid is equal to the weight of the fluid displaced by immersed part of the solid.