(i) When a body is immersed in a liquid, it experiences an upward thrust according to the Archimedes principle. The body will sink or float on the surface of the liquid depending on its density. There are three possibilities(iii) If the density of the body is equal to the density of the liquid, the body will remain in equilibrium anywhere within the liquid. The weight of the body is equal to the upward thrust exerted by the liquid. In this case the weight of the body is equal to the weight of the displaced liquid.(iv) If the density of the body is less than the density of the liquid, the body, when completely immersed in liquid, experiences an upward thrust more than its weight, the body moves up to the surface. In the equilibrium position the body floats. A part of the body is above the surface of the liquid and the other part is immersed in the liquid.Application of the principle of conservation of energy to the fluid flow leads to an important equation which was derived by Daniell Bernoulli in 1738. It states that the total energy of a small amount of an incompressible nonviscous liquid flowing without friction from one point to another, in a streamlined flow, remains constant throughout the displacement. Consider an element of liquid of mass ‘m’, density’. Its total energy ‘E’ is a sum equal to its kinetic energy, potential energy, and pressure energy.It can be seen that all three terms have the dimensions of length. The term v2/2g is called velocity head, his called gravitational head and p/dg are called pressure head. The names have been given to these terms per the cause of their origin.It states that in case of a small amount of an incompressible, nonviscous fluid, flowing from one point to another in a streamlined flow, the total of velocity head, gravitational head, and the pressure head is a constant quantityA solid body of density greater than that of water sinks while a body of density lowers than that of water floats.