PHYS-106 Fluids Part I Lecture Notes PDF

PHYSICS 106 HEALTH TRACK Fluids Part I Basic Sciences Department - Physics Section 1 Wednesday, 02 October 2024  Pre-Lecture Materials are available in “ONE DRIVE shared folder”....

PHYSICS 106 HEALTH TRACK Fluids Part I Basic Sciences Department - Physics Section 1 Wednesday, 02 October 2024  Pre-Lecture Materials are available in “ONE DRIVE shared folder”. Fluids: Pressure in fluids At the end of this lecture, the students will be able to: ✓ Discuss the density of solids, liquids and gases. ✓ Explain the statement of Pascal’s principle. Basic Sciences Department - Physics Section 2 Wednesday, 02 October 2024 Sec. 13.1: Fluids and Density | P. 433 ❖ What are the phases of matter? ❖ What is fluid? A fluid is simply a substance that flows. It takes the shape of its container. Fluids include liquids and gases. ❖ Why gases are compressible but not liquids? Basic Sciences Department - Physics Section 3 Wednesday, 02 October 2024 ❖ Why do cubes of the same size and shape have different masses? ❖ The mass density is the ratio of mass to volume: ❖ The SI units of mass density are kg/m3. ❖ Why does gasses have always lower densities compared to liquids and solids? Because the molecules in gases are farther apart than in liquids and solids. Basic Sciences Department - Physics Section 4 Wednesday, 02 October 2024 Check Your Understanding Q1: A piece of glass is broken into two pieces of different size. Rank in order, from largest to smallest, the mass densities of pieces 1, 2, and 3. 𝜌1 = 𝜌2 = 𝜌 3 ✓ The mass density is independent of the object’s size. ✓ The mass density is a characteristic property of the substance from which the object is made. Q2: Gases are compressible. This means that, for a given sample of a gas, A. the mass of the gas can be changed easily. B. the volume of the gas can be changed easily. C. the density of the gas can be changed easily. D. the volume and the density of the gas can be changed easily. E. the mass, the volume and the density of the gas can be changed easily. Basic Sciences Department - Physics Section 5 Wednesday, 02 October 2024 Sec 13.2: Pressure | P. 434 ❖ What is fluid pressure? Because the pressure inside is lower than the pressure outside. The pressure at a given point in the fluid is the ratio of the force to the area on which the force is exerted: 𝐹 𝑃= 𝐴 ❖ The SI unit of pressure, the pascal, is defined as: 1 Pa = 1 N/m2. ❖ The force due to a fluid’s pressure pushes on all parts of the fluid itself and on the walls of the container. Basic Sciences Department - Physics Section 6 Wednesday, 02 October 2024 Learning about Pressure To measure the pressure at any point within a fluid we can use the simple pressure-measuring device shown: Place the pressure-measuring device at different points in a fluid: Basic Sciences Department - Physics Section 7 Wednesday, 02 October 2024 Pressure in Liquids ✓ The force of gravity (the weight of the liquid) is responsible for the pressure in the liquid. ✓ The horizontal forces cancel each other out. ✓ The vertical forces balance. Because of our assumption that the fluid is at rest, this pressure is called hydrostatic pressure, and the equation above is called hydrostatic pressure equation. Basic Sciences Department - Physics Section 8 Wednesday, 02 October 2024 ❑ A connected liquid in ❑ In hydrostatic equilibrium, the hydrostatic equilibrium rises pressure is the same at all to the same height in all points in a horizontal line open regions of the through a connected liquid of container. a single kind. ❑ If we change the pressure at the surface from p0 to p0 + Δp, what will happen to the pressure p at a point at a depth d ? Basic Sciences Department - Physics Section 9 Wednesday, 02 October 2024 Check Your Understanding Q3: Rank in order, from largest to smallest, the pressure at A, B, C, D, E, and F. 𝑝𝐴 = 𝑝𝐵 = 𝑝𝐶 > 𝑝𝐷 > 𝑝𝐹 > 𝑝𝐸 Q4: If you dive under water, you notice an uncomfortable pressure on your eardrum due to the increased pressure. The human eardrum has an area of about 70 mm2 , and it can sustain a force of about 7 N without rupturing. If your body had no means of balancing the extra pressure, what would be the maximum depth you could dive without rupturing your eardrum? 𝜌𝑤𝑎𝑡𝑒𝑟 = 1000 kg/m3 A. 0.3 m B. 1 m C. 3 m D. 10 m Basic Sciences Department - Physics Section 10 Wednesday, 02 October 2024 Problem 13.9 | P. 461 A tall cylinder contains 25 cm of water. Oil is carefully poured into the cylinder, where it floats on top of water, until the total liquid depth is 40 cm. What is the gauge pressure at the bottom of the cylinder? 𝜌𝑜𝑖𝑙 = 900 kg/m3 Solution: 𝑝 = 𝑝0 + 𝜌𝑔ℎ 𝑝𝑔 = 𝑝 − 𝑝0 = 𝑝𝑔ℎ = 𝜌𝑤 𝑔 ℎ𝑤 + 𝜌𝑜𝑖𝑙 𝑔 ℎ𝑜𝑖𝑙 𝑝𝑔 = 1000 9.8 0.25 + 900 9.8 0.15 𝑝𝑔 = 2450 + 1323 = 3773 Pa ≈ 3.8 kPa Basic Sciences Department - Physics Section 11 Wednesday, 02 October 2024  12 CH. 13: Questions | Page 459 1, 2, 4, 13 and 34. CH. 13: PROBLEMS | Page 461 1, 11, 14 and 44. Basic Sciences Department - Physics Section 12 Wednesday, 02 October 2024 Basic Sciences Department - Physics Section 13 Wednesday, 02 October 2024