The paper "Physical Laws Governing Fluid Flow Resistance, and Pressure" is a great example of an assignment on physics. Fluids are those substances which have the property of flowing. Liquids and gases are fluids. The normal force acting per unit area on the surface of the fluid is called pressure. If A is the normal force acting on the unit area A then pressure P = F/A. The pressure impressed on a surface depends on the normal force applied and surface area. For the same force, if an area is small then the pressure will be large.
The pressure of a fluid can be explained using Bernoulli’ s principle. Bernoulli's Principle states that as the speed of a moving fluid increases, the pressure within the fluid decreases. Consider the case in which fluid passes through a pipe. The pressure of the fluid varies as per the size of the pipe hole. When the pipe hole narrows the fluid flows more quickly. Bernoulli's Principle tells that the pressure actually decreases as the fluid flows more quickly through the narrow sections. V2/2 + P/p +gz = constant where v is the velocity at a point, P pressure p density, g acceleration due to gravity and z the height above the reference level.
This equation relates the pressure, velocity, and height in the steady motion of an ideal fluid. The resistance to the flow of a fluid is associated with a viscosity of the fluid. The frictional force exerted by fluids is called viscous force. The property of fluid by virtue of which it opposes the relative motion between adjacent layers is called viscosity. It is the internal friction of the fluid.
In other words, the force required to move a plate at constant speed against the resistance of a fluid is proportional to the area of the plate and to the velocity gradient perpendicular to the plate. The constant of proportionality is called the viscosity. In fluids, viscous force is acting tangentially to the fluid layer opposing the flow. Therefore it is necessary to apply the external force to maintain the relative motion between fluid layers; otherwise, the motion of the fluids will be stopped due to internal friction. The principle of continuity states that, if an ideal fluid flows through a tube in streamline motion then the product of the cross-sectional area of the tube and the velocity of flow is same at every point in the tube.
If A is cross-sectional area and v is the velocity of flow of liquid then as per the principle of continuity Av = constant.