Fluid Mechanics with teacher's notes

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$Holt Math Minnesota Test Prep Workbook for Grade 9$

$Math Skills: More Practice$

67. In testing a new material for shielding spacecraft, 150 ball bearings each moving at a supersonic speed of 400.0 m/s collide head-on and elastically with the material during a 1.00 min interval. If the ball bearings each have a mass of 8.0 g and the area of the tested material is 0.75 m 2, what is the pressure exerted on the material? 68. A thin, rigid, spherical shell with a mass of 4.00 kg and diameter of 0.200 m is filled with helium at 0°C and 1 atm pressure. It is then released from rest on the bottom of a pool of water that is 4.00 m deep. a. Determine the upward acceleration of the shell. b. How long will it take for the top of the shell to reach the surface? Disregard frictional effects. Alternative Assessment Performance assessment 1. Build a hydrometer from a long test tube with some sand at the bottom and a stopper. Adjust the amount of sand as needed so that the tube floats in most liquids. Calibrate it, and place a label with markings on the tube. Measure the densities of the following liquid foods: skim milk, whole milk, vegetable oil, pancake syrup, and molasses. Summarize your findings in a chart or table. 2. Explain how you can use differences in pressure to measure changes in altitude, assuming air density is constant. How accurate would your barometer need to be to provide an answer accurate to one meter for a 55 m tall building, a 255 m tall building, and a 2200 m tall mountain? 3. The owner of a fleet of tractor-trailers has contacted you after a series of accidents involving tractortrailers passing each other on the highway. The owner wants to know how drivers can minimize the pull exerted as one tractor-trailer passes another going in the same direction. Should the passing tractor-trailer try to pass as quickly as possible or as slowly as possible? Design experiments to deter- Copyright © by Holt, Rinehart and Winston. All rights reserved. 69. A light spring with a spring constant of 16.0 N/m rests vertically on the bottom of a large beaker of water, as shown in Figure 9-27(a). A 5.00 × 10 −3 kg block of wood with a density of 650.0 kg/m 3 is connected to the spring, and the mass-spring system is allowed to come to static equilibrium, as shown in Figure 9-27(b). How much does the spring stretch? k (a) ∆x k m (b) Figure 9-27 mine the answer by using model motor boats in a swimming pool. Indicate exactly what you will measure and how. If your teacher approves your plan and you are able to locate the necessary equipment, perform the experiment. Portfolio projects 4. Record any examples of pumps in the tools, machines, and appliances you encounter in one week, and briefly describe the appearance and function of each pump. Research how one of these pumps works, and evaluate the explanation of the pump’s operation for strengths and weaknesses. Share your findings in a group meeting and create a presentation, model, or diagram that summarizes the group’s findings. 5. You have been hired as a consultant to help the instructors of a diving school. They want you to develop materials that explain the physics involved in the following diving-safety rules: diving tanks must be kept immersed in cold water while they are being filled, and divers must exhale while ascending to the surface. Use the gas laws to explain what dangers (if any) these rules are designed to prevent. Fluid Mechanics 349 9 REVIEW & ASSESS 67. 21 Pa 68. a. 0.48 m/s 2 b. 4.0 s 69. 1.7 × 10 −3 m Alternative Assessment ANSWERS Performance assessment 1. Students should realize that the higher the tube floats (more buoyant force), the greater the fluid’s density. 2. All of the heights require a precision of 1 m. That corresponds to 13 Pa, given ∆P = rgh. 3. Student plans should be safe and should measure force or acceleration perpendicular to the motion. When boats or trucks pass, the speed of the fluid between them increases (as in a narrow pipe), and pressure drops. 4. Student answers Portfolio should recognize that projects pumps use pressure differences to move fluids. Possible answers include: air pump for tires, gas pump, or vacuum cleaner. 5. If the air is hot when the tank is filled, a smaller amount of air will fit in the tank. As divers rise to the surface, pressure drops to 1 atm, and the volume of air in the lungs expands. 349
Chapter 9 Laboratory Exercise NOTE Materials Preparation is given on pp. 316A–316B. Blank data table and sample data table are on the One-Stop Planner CD-ROM. All calculations are performed using sample data. Planning Recommended time: 1 lab period Classroom organization: This lab may be performed by students alone or in pairs. The CBL and sensors procedure and the Boyle’s law apparatus may be used in the same class. Safety warnings: This is a low-risk laboratory experiment. Remind students to follow all standard laboratory rules and procedures. 350 OBJECTIVES •Measure the volume and pressure of a gas at constant temperature. •Explore the relationships between the volume and pressure of a gas. MATERIALS LIST ✔ Check list for appropriate procedure. PROCEDURE CBL AND SENSORS ✔ CBL ✔ graphing calculator with link cable ✔ CBL pressure sensor with CBL-DIN adapter and syringe ✔ airline tubing (10 cm) BOYLE’S LAW APPARATUS ✔ Boyle’s law apparatus ✔ set of five 1 kg masses 350 Chapter 9 CHAPTER 9 Laboratory Exercise BOYLE’S LAW The ideal gas law states the relationship between the temperature, pressure, and volume of a confined ideal gas. At room temperature and atmospheric pressure, air behaves nearly like an ideal gas. In this lab, you will hold the temperature constant and explore the relationship between the volume and pressure of a fixed amount of air at a constant temperature. Because the air will be contained in an airtight syringe, the quantity of gas will be constant throughout the experiment. You will perform this experiment using either a CBL with pressure sensor or the Boyle’s law apparatus. • CBL and sensors You will use the pressure sensor to measure the pressure of the air at different volumes, starting with an initial volume of 10 cm 3 and decreasing by 1 cm 3 increments. You will graph your data and analyze the graphs to find the relationship between pressure and volume for a gas. • Boyle’s law apparatus You will increase the pressure on a fixed quantity of air in a syringe by adding weight to the end of the plunger. As the pressure is increased, you will measure the change in volume using the markings on the syringe. You will graph your data and analyze the graphs to find the relationship between pressure and volume for a gas. SAFETY • Tie back long hair, secure loose clothing, and remove loose jewelry to prevent their getting caught in moving or rotating parts. • Wear eye protection. Contents under pressure may become projectiles and cause serious injury. PREPARATION 1. Determine whether you will be using the CBL and sensors procedure or the Boyle’s law apparatus. Read the entire lab for the appropriate procedure, and plan what steps you will take. Boyle’s law apparatus procedure begins on page 352. Copyright © by Holt, Rinehart and Winston. All rights reserved.
Page 1 and 2: Chapter 9 Overview Section 9-1 defi
Page 3 and 4: Section 9-1 Demonstration 1 Volume
Page 5 and 6: SECTION 9-1 The Language of Physics
Page 7 and 8: SECTION 9-1 Demonstration 4 Lifting
Page 9 and 10: SECTION 9-1 PRACTICE GUIDE 9A Solvi
Page 11 and 12: SECTION 9-2 STOP 326 Misconception
Page 13 and 14: SECTION 9-2 Visual Strategy Figure
Page 15 and 16: SECTION 9-2 Classroom Practice The
Page 17 and 18: Section 9-3 Demonstration 7 Fluid f
Page 19 and 20: SECTION 9-3 Misconception STOP Aler
Page 23 and 24: Section 9-4 Demonstration 10 Temper
Page 27 and 28: Chapter 9 Summary Teaching Tip Ask
Page 29 and 30: 9 REVIEW & ASSESS 12. because the p
Page 31 and 32: 9 REVIEW & ASSESS 42. 7.1 m 43. 17
Page 33: 9 REVIEW & ASSESS 63. 60.9 m/s 2 64
Page 37 and 38: CHAPTER 9 LAB Boyle’s Law Apparat

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