NCERT Solutions for Class 11 Physics Ch-9: Mechanical Properties of Fluids

Answer: Pascal's law states that pressure applied to an enclosed, incompressible fluid is transmitted equally and undiminished in all directions throughout the fluid. It is applied in devices such as the hydraulic lift and hydraulic brakes, where a small force applied over a small area can produce a much larger force over a larger area.

Answer: Archimedes' principle states that when a body is partially or fully immersed in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the body.

Answer: Bernoulli's principle states that for an ideal, incompressible, and non-viscous fluid in streamline flow, the sum of pressure energy, kinetic energy, and potential energy per unit volume remains constant along a streamline: P + (1/2)ρv² + ρgh = constant.

Answer: Viscosity is the property of a fluid by virtue of which it opposes relative motion between its adjacent layers. Stokes' law states that the viscous drag force on a small sphere moving through a viscous fluid is given by F = 6πηrv, where η is the coefficient of viscosity, r is the radius of the sphere, and v is its velocity.

Answer: Surface tension is the property of a liquid surface that makes it behave like a stretched elastic membrane, tending to minimize its surface area, defined as the force acting per unit length along the surface. Liquid drops take a spherical shape because, for a given volume, a sphere has the minimum possible surface area, which minimizes the surface energy due to surface tension.