Which of the following has no dimensions?

Dimensions refer to the physical nature of a quantity and are expressed as powers of fundamental units like mass (M), length (L), and time (T). They help derive relationships between quantities verify equations and check consistency. For example, force has dimensions of MLT⁻² representing its fundamental components.

Chapter 8 of Class 11 Physics, Mechanical Properties of Solids, explains how solids respond to external forces through deformation. It covers stress, strain, Hooke’s law, Young’s modulus, bulk modulus and shear modulus. Topics include elastic potential energy, Poisson’s ratio and applications of elasticity. These concepts are essential for understanding the mechanical behavior of materials in various conditions.