Science 7 Unit 3 Heat and Temperature Name:_ Class:_
TOPIC 1 REINFORMCEMENT Putting Thermal Energy to Work Goal Develop ways to classify natural and manufactured structures. BLM 3-1 When do you use thermal energy? Imagine that it is an average, mid-winter school day. In what situations do you use or need thermal energy (heat)? Read the following sentences and complete each with a word from the list below. 1. When you get up in the morning, the house is warm. The kept the house warm all night and will keep it warm during the day. 2. In the bathroom you notice a lightbulb is burnt out. The bulbs that are lit are hot and give off in addition to light. The burnt-out bulb is still cold. 3. The makes and stores hot water for your home. The hot shower soon makes the bathroom. 4. Hot air from the evaporates the water from your hair. 5. You need some porridge to keep you warm today. The boils water for the instant porridge. 6. The coat, gloves, boots and hat you wear help keep your where you need it in and around you. 7. As you walk into the school, you feel a blast of hot air. Thank goodness the custodian keeps the well maintained! 8. Words to use: Boiler, hair dryer, furnace, kettle, steamed up, hot water heater, body heat, heat In the situation described above, several sources of thermal energy that humans use are mentioned or described. Use them to fill in the chart. 1. 2. 3. 4. 5. 6. 7. Thermal Energy Sources How Humans use this Heat Source DATE: NAME: CLASS:
TOPIC 2 How Different Thermometers Work BLM 3-3 Goal Compare the designs of different thermometers and understand how they work. Think About It The first thermometer was built in 1593 by Galileo, a famous Italian scientist. Since then, other scientists have experimented with different designs. Today s thermometers might look different from the early models, but the theory behind them has not changed. Use the space provided, or a separate page, to answer the following questions, Use Figures 3.4A, B, and C in your textbook to help you. 1. How are an air thermometer and a liquid thermometer different? 2. (a) What features do a liquid thermometer and a lab thermometer have in common? (b) How are they different? 3. (a) What change occurs in the liquid inside a thermometer when the thermometer is placed in something hot? (b) What change occurs when the thermometer is placed in something cold? 4. What is the advantage of having the liquid move up a narrow bore?
TOPIC 2 How Different Thermometers Work (continued) BLM 3-3 5. A clinical thermometer is used to measure the temperature of a human. (a) The scale is calibrated in degrees Celsius. It shows a range from 35 C to 42 C. Why is a clinical thermometer made to measure only temperatures in this narrow range? (b) The glass stem is designed to act as a magnifying glass. Why is the stem designed this way? (c) The glass around the bulb is relatively thin. Why is the glass so thin? (d) Why is the bore narrower directly above the bulb?
TOPIC 2 SKILL BUILDER Reading a Thermometer Goal Review how to read a thermometer accurately. BLM 3-4 Think About It When experimental measurements are made, errors can be caused by carelessness. The most common errors are parallax errors and reading errors. A parallax error occurs when your eye is not placed directly opposite the scale where the reading is being taken. When reading the liquid level, your eye must be lined up with the top and bottom of the meniscus. A reading error occurs when you must estimate because the liquid lies somewhere between scale divisions. Try to estimate as accurately as possible, to the nearest half degree. Use the information above to help you answer the following questions. 1. What is the temperature reading indicated by each thermometer? 2. Draw a thermometer to illustrate each of the temperatures below. (a) 52.0 C (b) 2.0 C (c) 20.5
TOPIC 2 What is Energy? Goal Develop a complete understanding of the concept of energy. BLM 3-8 Read about energy in your text and then complete the following chart. Compare the examples and place a check mark in the appropriate column. The first example is done for you. A fully charged (new battery) A used (uncharged) battery A candle A campfire School P.A. system A rock concert s speaker system A ping-pong ball after it is hit A golf ball after it is hit Statement More Energy Less Energy 1. Energy can be transferred. 2. Particles (mass) can be moved (transferred). 3. Energy has mass. 4. Particles have mass. 5. Energy makes particles move. 6. Moving particles have energy. 7. Energy can flow on its own. 8. Particles can start to move on their own (by themselves). 9. Heat energy flows from colder to hotter areas. 10. Energy from burning of gas in a hot air balloon transfers to the air around it. 11. An ice cube has no energy.
TOPIC 3 Temperature Versus Thermal Energy BLM 3-9 Goal Reinforce the concepts of temperature and thermal energy Think About It Temperature is a measure of the average energy of the particles in a material. Thermal energy is the total energy of all the particles in the material. Review the definitions of temperature and thermal energy given above. Answer the following questions in the space provided. 1. (a) Why is the temperature of the little bit of soup in the spoon the same as the temperature of the larger volume of soup in the bowl? (b) Although their temperatures are the same, the bowl of soup has more thermal energy than the spoonful of soup. Explain why. 2. Suppose you have the following four beakers of water. (a) Use the particle model to describe what happens when the hot water in the first or second beaker is poured into one of the beakers of cold water.
TOPIC 3 Temperature Versus Thermal Energy (continued) BLM 3-9 (b) Suppose you poured the hot water in the first beaker into one beaker of cold water. Then you poured the hot water in the second beaker into the other beaker of cold water. Which mixture would have a greater temperature? (c) Would your answer in part (b) be different if the temperature of the ¼ L of hot water was much higher than the temperature of the ½ L of hot water? (d) On which two factors does the final temperature of a mixture of hot and cold water depend?
TOPIC 5 VOCABULARY CHECK Learn the Lingo BLM 3-18 Goal Learn the vocabulary that describes changes of state. Think About It There are six possible changes of state, as shown by the arrows on the diagram below. Several of the changes have common names, which you probably know. Some of the changes are identified by technical terms used in science. It will be easier for you to describe and read about changes of state if you learn and practise using both their common and technical names. Answer the following questions in the space provided. 1. Above the correct arrow in the diagram, write each technical term from the table. Also write (in brackets) the common term for the change, if there is one. Notice that one technical term is used to describe two different changes. Term solidification (freezing) condensation sublimation evaporation fusion (melting) sublimation Change liquid to solid gas to liquid gas directly to solid liquid to gas solid to liquid solid directly to gas
TOPIC 5 VOCABULARY CHECK Learn the Lingo (continued) BLM 3-18 2. Read each statement below. Then write a description of each statement, using a technical term, as in the example. Wet clothes dry in the sunshine. Description: evaporation of liquid water (a) Melted wax in a candle hardens when the candle is blown out. Description: (b) A warm wind makes snow on the ground disappear, but no puddles of water form. Description: (c) In the winter, invisible moisture in the air sometimes forms frost on car windshields. Description: (d) On a cold day, you can see your breath. Description: 3. Classify the six changes of state according to the change of thermal energy they involve. Arrange your answers in a table, with headings Receiving thermal energy and Releasing thermal energy.
TOPIC 6 Radiation BLM 3-20 Goal Check your knowledge and understanding of radiation. Answer the following questions in the space provided. Use full sentences. 1. When you sit in front of a fire, you feel warmed by radiant energy. When someone stands between you and the fire, you feel cold again. Explain why this happens. Draw and label a diagram to illustrate your explanation. 2. Why are white or light-coloured clothes recommended for hot, sunny locations? 3. Why did the Apollo astronauts wear shiny suits on the moon?
TOPIC 6 Radiation (continued) 4. Explain how insulation between the outer and inner walls of a home helps to reduce thermal energy transfer. BLM 3-20 5. Explain how a reflective film on windows helps to keep a home cool in the summer but warm in the winter. DATE: NAME: CLASS: Conduction Answer the following questions in the space provided. Use full sentences. 1. On a cold winter day, why would an iron post in a park feel much colder to the touch than a wooden bench? 2. Potatoes cook from the outside in. (a) Why does a small potato cook faster than a large potato? (b) Why does sticking a metal skewer through the middle of a potato make it cook faster?
TOPIC 6 Convection BLM 3-22 Goal Apply your knowledge and understanding of convection currents in nature. Answer the following questions in the space provided. 1. Sea and land breezes are convection currents that occur in nature. Warmer air rises and cooler air moves in to take its place. (a) During the day, the land heats up faster than the sea. The warmer air above the rises. This allows the sea air to move in, causing a sea breeze. In the space below, draw and label a diagram of the air currents during a hot, sunny day by the sea. During the night, the land cools faster than the sea. The warmer air above the rises. The cooler air over the moves in to take its place, creating a land breeze. In the space below, draw and label a diagram of the air currents during a night by the sea.
(b) Under what conditions would no breezes occur? (c) Explain how cold temperatures along a beach affect the direction of a sea breeze. 2. During the winter, colder water near the surface of a pond sinks. Warmer water at the bottom of the pond rises. (a) Why does a small potato cook faster than a large potato? (b) Can you suggest a reason why ponds become stagnant in the summer? 3. Find out more about warm air currents. How can birds use warm air currents?
TOPIC 7 Solar Homes BLM 3-32 Goal Reinforce your understanding of the energy transfer systems in solar homes. Introduction Most solar homes are built with a solar collector mounted on the roof. The solar collector consists of water-filled pipes beneath a layer of energy-absorbing material. The water is heated by the collected solar energy. It travels down through the pipes to a large, insulated water tank in the basement of the home. The heat is distributed from this tank to the rest of the home by a distribution system of air ducts and heat vents. Study this diagram of a typical solar home. Then answer the following questions in the space provided.
TOPIC 7 Solar Homes (continued) 1. (a) What is the purpose of the ridges on the roof? BLM 3-32 (b) What type of material should be used to construct the ridges? 2. What role do the pipes play in the operation of the solar home? 3. Describe how the collected heat is stored and distributed to the interior of the home. 4. Explain how a pump could be used to control the amount of heat distributed throughout the home.