CHAPTER 4 ANSWER KEY BLM 4-1, Steam Engine Designs/ Overhead Master Answers not applicable BLM 4-2, The Changing Face of the Steam Engine/Skill Builder Goal: Students develop a detailed understanding of some steps in the evolution of the steam engine. 3. Answers 1. The fire caused the water in the kettle to boil. When the liquid water turned into steam, its volume increased and the steam was pushed up the two pipes that supported the hollow ball above the kettle. The only way for the steam to escape from the hollow ball was through the curved pipes on the sides of the ball. As the steam was pushed out of the curved pipes, it pushed back so hard that it made the pipes and, consequently, the ball move in the opposite direction to the steam. Since the ball was attached to an axle, the ball rotated when the steam pushed out of the curved tubes. This motion is similar to the movement of a balloon that has been blown up and released. 2. 4. 5. 6. 7. 8. 9. 10. - - - - - The water boiled into steam. Valve C was opened, and the steam went into vessel D. · · · · · · Valve C was closed and valve V1 was opened. The steam condensed back into water, creating a vacuum in vessel D. The vacuum above the water in the lower pipe exerted less pressure on the water in the mine than did the atmosphere above the water outside the pipe. As a result, the atmospheric pressure pushed the water up the pipe into vessel D. Valve V1 was closed and valves C and V2 were opened. Steam from the boiling water now pushed the water out of vessel D and up pipe E to G, where it was expelled. During the second step in the cycle of Savery’s steam engine, when a vacuum formed in the vessels labelled D in the diagram, atmospheric pressure above the water in the mine pushed the water up the pipe into the vessels. During the last step in the cycle of Savery’s steam engine, steam pressure from the boiler pushed the water in the vessels labelled D up the pipes labelled E to pipe G, where it was expelled. (a) When steam was allowed into the cylinder, the steam pressure below the piston was greater than the atmospheric pressure above the piston, causing the piston to rise. (b) When the valve to the boiler was closed and water was sprayed into the cylinder, the cylinder was cooled. The lowering of the temperature caused the steam to condense. The condensing of the steam reduced the pressure below the piston. Then the atmospheric pressure above the piston was higher than the pressure inside the cylinder. The atmospheric pressure thus pushed the piston down. The cold water was needed in Newcomen’s steam engine to cool the piston and condense the steam, thus creating a vacuum. In Watt’s steam engine, steam pressure pushed the piston both ways. Since steam acted on the piston twice in one complete cycle, the engine was called a “double-acting” engine. The valve in Watt’s steam engine moved one way to direct the steam to one side of the piston and then moved the other way to direct the steam to the opposite side of the piston. Since the cylinder in Watt’s steam engine was always hot, the cylinder and piston were not subjected to frequent heating and cooling. In steam engines that were used before Watt developed his engine, extreme changes in the temperature of the metals caused the metals to expand and contract. This resulted in serious wear and tear on the parts. Watt invented systems of levers and a crank shaft that allowed the steam engine to turn a large wheel. A belt connected the wheel of the engine to other wheels, which could run many types of machines. Copyright © 2004 McGraw-Hill Ryerson Limited. Permission to edit and reproduce this page is granted to the purchaser for use in her/his classroom. McGraw-Hill Ryerson shall not be held responsible for content if any revisions, additions, or deletions are made to this page. CHAPTER 4 ANSWER KEY Extend Your Skills 11. Since over 70 of the devices that were sketched by Hero can be found on the Internet, students’ answers will vary. One of the interesting devices is shown here. When a fire is lighted on the altar, it heats the air in the altar. A rod passes down into the water in the base of the pedestal. The heated air expands and moves into the water. The extra pressure pushes the water up, through pipes in the statues to the vessels in the statues’ hands. The water pours out from the vessels and extinguishes the fire on the altar. Child Labour 1. Children worked in textile mills, changing spools and operating the machinery. They worked in breaker rooms of coal mines, sorting and breaking pieces of coal. They worked in glass factories, holding molds. They also worked in canneries. 2. In the early days of the Industrial Revolution, it was common for children as young as seven years old to work in factories. 3. In the early days of the Industrial Revolution, children worked up to 18 h a day, six days a week. They typically earned about one dollar a week. 4. By the late 1800s, many laws were passed that were intended to improve working conditions and prevent child labour. However, these laws were often ignored. It was not until the late 1930s that laws were passed and enforced in North America to limit the number of work hours and prevented child labour. Working Conditions 12. Metals expand and contract when heated and cooled. When metal parts that are connected expand and contract, the connections can be damaged. Spacers are built into structures such as bridges. When the metal parts expand or contract, the spacers are designed to open further or close. This design prevents excessive stress and strain on the metal parts as well as concrete. BLM 4-3, Science, Technology, and the Industrial Revolution/Science Inquiry Goal: Students clearly understand the impact that a new technology, the steam engine, had on society and the environment. Answers Answers will vary depending on the sources. Below are some possible answers that students might find on the Internet or in print resources. 1. In the early 1800s, factory labourers worked from 12 to 18 h a day, six days a week. 2. Children earned about one dollar a week. Adults earned four or five dollars a week. 3. The air in textile mills was filled with lint, which could cause respiratory diseases. The large, heavy machines were not protected. Children might dose off and fall and be injured by a machine. The factories were cold and drafty in the winter and hot and humid in the summer. Stonemasons lived, on average, to only 36 years of age due to breathing the dust. 4. Methane gas could collect in a coal mine and explode. Ground water could seep into a mine and trap miners. Breathing coal dust caused serious respiratory damage. 5. It was not until about 1910 that safety in the workplace became a social issue. Significant changes in workplace safety took place between 1910 and 1929. When laws were passed to compensate workers who had been injured in the workplace, factory owners began to improve safety conditions. 6. The 8 h workday was discussed by some reformers in the mid-1800s. It was not until the 1950s, however, that the 40 h workweek was generally accepted throughout North America and Europe. 7. One of the first mine safety laws was passed in 1891. These first laws were not strict but have been improved, step by step, over the years. Pollution 1. Refuse from mines, solvents from textile dyeing, cleaning and tanning solvents from leather tanning, garbage from slaughterhouses, and sewage were dumped directly into rivers during the early years of the Industrial Revolution. Copyright © 2004 McGraw-Hill Ryerson Limited. Permission to edit and reproduce this page is granted to the purchaser for use in her/his classroom. McGraw-Hill Ryerson shall not be held responsible for content if any revisions, additions, or deletions are made to this page. CHAPTER 4 ANSWER KEY 2. The famous physicist Michael Faraday wrote a very poignant letter to the editor of a newspaper, describing the filth of the River Thames in London. Ellen Swallow Richards (1842–1911), the first woman to be accepted into MIT (Massachusetts Institute of Technology), was an early campaigner for clean water. She earned a degree in chemistry and carried out tests on water purity. 3. Several laws were passed in the 1860s and 1870s in Europe and North America, limiting air and water pollution. BLM 4-4, Using GRASP to Solve Problems/Reinforcement Goal: Students develop a structured thinking process that will help them solve problems. Answers 1. Answers will vary but should follow the general steps in the sample answer below. Given: Will be jogging outside today Will be going for job interview after school Forgot to do laundry Required: Must be dressed for both jogging outside and going to a job interview Analysis: Clothing must be clean. It must be comfortable and cool for jogging, and neat for interview. Layered clothing will permit comfort and neatness. Solution: Wear T-shirt with good shirt or light sweater over it. Take off shirt or sweater, and jog in T-shirt. Wear nice pants, not jeans. Pants must be loose enough for jogging and neat enough for interview. Paraphrase: Wear T-shirt and loose pants for jogging. Add good shirt or light sweater for interview. 2. Answers will vary but should follow the general steps in the sample answer below. Given: Critical exam in required course tomorrow Must pass course to take sequential course next year Future plans require passing these courses Friends practising favourite sport Tryouts in three days Making varsity team will help achieve plans for coaching career Required: Must decide what is most beneficial for being accepted into university program in coaching Analysis: Is it possible to practise with friends and then study enough to pass the exam tomorrow? Which is more critical for a future career in coaching: passing the exam or making the varsity team? Decide not to take chances. Solution: Stay home and study. If you don’t pass the courses you need, making the varsity team will have little influence on getting into the university program. Paraphrase: Stay home and study. 3. Given: Must raise $1000 Have $275 Earn $8.50/h 15% withheld for taxes 12 h worked per week Time remaining Dec. 1 to Oct. 1 Required: $1000 by Dec. 1 Analysis: Determine number of hours to be worked by Dec. 1 to get money earned by Dec. 1. Add money earned to amount already in bank, and compare total with $1000 needed. Solution: Days in October = 31 Days in November = 30 Total days remaining = 61 Weeks remaining = 61 days 8.7 weeks 7 days per week Work hours = 8.7 weeks 12 h/week = 104.4 h 104 h Money to be earned = 104 h $8.50/h = $884 Money to be earned minus taxes withheld = $884 ($884 0.15) Money to be earned minus taxes withheld = $884 $132.60 Money to be earned minus taxes withheld = $751.40 Money earned plus savings = $751.40 + $275 Money earned plus savings = $1026.4 $1026.4 is greater than $1000. Paraphrase: You will have $26.40 more than you need for the trip. You can go! 4. Given: Distance to bus = 20.8 km Time to reach bus = 20 min Speed limit for 8.5 km = 50 km/h Speed limit for 12.3 km = 80 km/h Required: Time required to reach bus Analysis: Find time to go first 8.5 km. Find time to go last 12.3 km. Add times together, and compare total with 20 min. Copyright © 2004 McGraw-Hill Ryerson Limited. Permission to edit and reproduce this page is granted to the purchaser for use in her/his classroom. McGraw-Hill Ryerson shall not be held responsible for content if any revisions, additions, or deletions are made to this page. CHAPTER 4 ANSWER KEY 8.5 km 50 km/h Time to go first 8.5 km = 0.17 h 12.3 km Time to go first 8.5 km = 80 km/h Time to go first 8.5 km = 0.154 h Total time = 0.17 h + 0.154 h Total time = 0.324 h 60 min Total time = 0.324 h h Total time = 19.44 min 20 min is greater than 19.44 min. Paraphrase: If you are not slowed by traffic and you do not hit any red lights, you will get to the bus in time. Solution: Time to go first 8.5 km = BLM 4-5, Energy and Work Practice Problems/Skill Builder Goal: Students practise solving problems that involve work. Answers 1. 1.2 102 J 2. 2.33 106 J 3. (a) 4.4 103 J (b) None. The direction of the force was perpendicular to the direction of the motion. 4. 2.330 m 5. 2.50 102 m 6. 0.16 m 7. 1.3 103 N 8. (a) 3.9 103 J (b) 1.8 m BLM 4-6, Graphical Methods for Determining Work/Skill Builder Goal: Students determine work done using force versus position graphs. Answers 1. (a) (b) (c) 2. (a) (b) 42 J 17.5 J 40 J approximately 77.5 J approximately 253 J BLM 4-7, Fuelled by Farm Waste/Science Inquiry Answers Essays will vary significantly. The essays should resemble the examples given in the BLM. BLM 4-8, Chapter 4 Test/Assessment Goal: Students demonstrate their understanding of the information presented in Chapter 4. Answers 1. F: James Watt improved the design of the Newcomen steam engine. 2. F: Modern scientists accept the kinetic-molecular theory of heat. 3. T 4. F: Temperature is a measure of the average kinetic energy of the atoms and molecules in an object. 5. T 6. (d) 7. (a) 8. (e) 9. (b) 10. (c) 11. turbine 12. area under the curve 13. internal combustion 14. kinetic-molecular 15. less than 16. (d) 17. (b) 18. (d) 19. (a) 20. (b) 21. (b) 22. (d) 23. (a) 24. (c) 25. (a) 26. 1 . 2 3 27. 1 . 1 0 2 28. 2 . 3 4 3 29. James Joule hung a weight on a string over a pulley. The string was wrapped around an axle, which was attached to a paddle wheel. The paddle wheel was immersed in water. When the weight fell, it turned the paddle wheel in the water. James Joule measured the distance that the weight fell and the increase in the temperature of the water. He related the loss in gravitational potential energy of the weight to the gain in the temperature of the water. He calculated the amount of mechanical energy that was transformed into heat in the water. Goal: Students expand their knowledge of methods that are being developed to conserve energy while protecting the environment. Copyright © 2004 McGraw-Hill Ryerson Limited. Permission to edit and reproduce this page is granted to the purchaser for use in her/his classroom. McGraw-Hill Ryerson shall not be held responsible for content if any revisions, additions, or deletions are made to this page.