46-(a) State Pascal's law?
(b) Define upthrust or buoyant force. Describe an activity to show that a body loses its weight when
immersed in a liquid?
Answers
Explanation:
(a)Pascal's Law is the principle behind hydraulic lifting and pressing devices
Pascal's law (also Pascal's principle[1][2][3] or the principle of transmission of fluid-pressure) is a principle in fluid mechanics given by Blaise Pascalthat states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.[4] The law was established by French mathematician Blaise Pascal [5] in 1647–48.[6]
DefinitionEdit

Pressure in water and air. Pascal's law applies for fluids.
Pascal's principle is defined as
A change in pressure at any point in an enclosed fluid at rest is transmitted undiminished to all points in the fluid.
This principle is stated mathematically as:
{\displaystyle \Delta P=\rho g(\Delta h)\,}{\displaystyle \Delta P} is the hydrostatic pressure (given in pascals in the SI system), or the difference in pressure at two points within a fluid column, due to the weight of the fluid;ρ is the fluid density (in kilograms per cubic meterin the SI system);g is acceleration due to gravity (normally using the sea level acceleration due to Earth's gravity, in meters per second squared);{\displaystyle \Delta h} is the height of fluid above the point of measurement, or the difference in elevation between the two points within the fluid column (in meters).
The intuitive explanation of this formula is that the change in pressure between two elevations is due to the weight of the fluid between the elevations. Alternatively, the result can be interpreted as a pressure change caused by the change of potential energy per unit volume of the liquid due to the existence of the gravitational field.[further explanation needed] Note that the variation with height does not depend on any additional pressures. Therefore, Pascal's law can be interpreted as saying that any change in pressure applied at any given point of the fluid is transmitted undiminished throughoutthe fluid.
The formula is a specific case of Navier–Stokes equations without inertia and viscosity terms
(b) Buoyancy (/ˈbɔɪənsi, ˈbuːjənsi/)[1][2] or upthrust, is an upward force exerted by a fluid that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the pressure at the bottom of a column of fluid is greater than at the top of the column. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. The pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and (as explained by Archimedes' principle) is equivalent to the weight of the fluid that would otherwise occupy the volume of the object, i.e. the displaced fluid.
For this reason, an object whose average density is greater than that of the fluid in which it is submerged tends to sink. If the object is less dense than the liquid, the force can keep the object afloat. This can occur only in a non-inertial reference frame, which either has a gravitational field or is accelerating due to a force other than gravity defining a "downward" direction.[3]
The center of buoyancy of an object is the centroid of the displaced volume of fluid.