General Physics (PHYS 101) Lecture Notes PDF

Physics Department General Physics (PHYS 101) Updated By: Dr.Najah Alwadie 1 2024 - 1446 [email protected]  :Lecture 5Fluid Mechanics Chapter 14 - From P402 to P432 2  Outlines Fluid...

Physics Department General Physics (PHYS 101) Updated By: Dr.Najah Alwadie 1 2024 - 1446 [email protected]  :Lecture 5Fluid Mechanics Chapter 14 - From P402 to P432 2  Outlines Fluid and Fluid Mechanics Fluid Statics Density Pressure Variation of Pressure with Depth Pascal’s law Pressure Measurements Buoyant Forces-Archimedes Principle Fluid Dynamics Viscosity Equation of Continuity for Fluids Bernoulli's Equation Torricelli’s Law 3  What is the meaning of Fluid Matter is normally classified as being in one of four states: solid, liquid, gas, and plasma. All of liquids, gases, and plasma are fluids. A fluid is a collection of molecules that are randomly arranged and held together by weak cohesive forces and by forces exerted by the walls of a container. Fluid Mechanics Fluid mechanics is the study of how fluids move and the forces on them. Fluid mechanics can be divided into: fluid statics, the study of fluids at rest...the study of fluids in motion ,fluid dynamics  Density Density is defined as: amount of matter per unit volume In other word: is the ratio of mass to volume. r = m\ v The SI unit of density is the kilogram per cubic meter.A homogeneous material such as ice or iron has the same density throughout Is it a scalar or vector quantity? 6  Densities of Some Common Substances 7  Pressure Pressure is defined as force per unit area. The standard unit for pressure is the Pascal, which is a Newton per square meter. Is it a scalar or vector quantity? 8  Density 9  Variation of Pressure with Depth If the fluid is open to the atmosphere of pressure, the pressure of the fluid at a depth is given by:.The pressure in a fluid changes linearly with depth The atmospheric pressure 10 Pascal’s law ‘‘ A change in the pressure applied to an enclosed liquid is transmitted undiminished to every point of the liquid and to the walls of the container. ’’ In the case of hydraulic press, if the force at one piston of area A 1 is F1 , this pressure is transmitted through a liquid to the other piston of area. This produces a force at the.other piston :Since the pressure is the same at both pistons, this gives  Pascal’s law 12  Pressure Measurements Two devices for measuring pressure: mercury barometer. open-tube manometer. The pressure at B, however, equals the The closed end of the tube is nearly a pressure at A, which is also the unknown vacuum, so its pressure can be taken to pressure P. We conclude that be zero. It follows that The barometer measures The manometer measures the pressure of the pressure in an enclosed fluid. atmosphere 13  Buoyant Forces-Archimedes Principle 14 Buoyant Forces-Archimedes Principle Law of Archimedes: The buoyant force is equal to the weight of.the replaced liquid or gas Viscosity Viscosity is internal friction in a fluid. Due to viscosity, the speed is zero at the pipe walls (to which the fluid clings) and is greatest at the center of the pipe.  Viscosity 17 Viscosity : The viscosity force F is given as #$ #$ !" ! =& % %.where A is the surface area.v is the velocity.d is the distance between the two plates. is the viscosity coefficient  Equation of Continuity for Fluids The product of the area and the fluid speed at all points along a pipe is constant for an incompressible.fluid :The equation of continuity for fluids states that 19  Bernoulli's Equation This expression shows that the pressure of a fluid decreases.as the speed of the fluid increases.In addition, the pressure decreases as the elevation increases 20 Bernoulli's Equation  Torricelli’s Law Torricelli's law, also known as Torricelli's theorem, is relating the speed of fluid flowing out of an opening to the height of fluid above the.opening ,If the tank is open to the atmosphere.then P = P0 and 22  Problems & Exercises 23  Physics Department Problems Problem ( no.1 page 423 ) -1 Problem ( no. 7 Page 424 ) -2 Problem ( no. 51 Page 428 ) -3 24 25