Fluid Force:

The surface forces depend upon the surface area of contact and don't depend upon the volume of fluid. A fluid at rest exerts pressure-to which Bernoulli called "static pressure"-on its container. On the other hand, forces of body depend upon the volume of substance and are distributed through the fluid element. Examples of it are weight of any substance, electromagnetic forces etc .Surface forces are brought about by contact of fluid with the other fluid. In Fluid Mechanics we consider the forces upon fluid elements. It is essential to discuss the type of forces which could act on fluid elements. These Forces could be divided into 2 categories - Surface Forces, and Body Forces. According to the Bernoulli's principle, the greater the velocity of flow in the fluid, the greater the dynamic pressure and the less the static pressure. In a cylindrical pipe, static pressure can be exerted to the surface of the container, while dynamic pressure is parallel to it.

The region of relative motion among the adjacent layers of fluid particles. This friction differs from fluid to fluid. A static fluid have no shearing force acting on it, and that any force between the fluid and the boundary should be acting at right angles to the boundary. The drag caused by the fluid tending to rub the surface of the body. The thin layer of fluid in contact with solid surface of the body does not slide. The balloon itself can be "heavier than air," but it is not as heavy as the air it has displaced. If an object immersed in fluid a balloon in the air or a ship on the ocean weighs less than the amount of fluid it displaces, it will float. If it weighs more, it will fall or sink. Similarly, an aircraft carrier contains a vast weight in steel and other material, yet it floats, because its weight is not as large as that of the displaced water. In other words, slower-moving fluid exerts larger pressure than faster-moving fluid. The discovery of this principle made possible the development of the airplane.