Water absorption 12. It unit is mho/meter. Suggest three possible uses of a material that is a good conductor of electricity. Learners may say the paper that is most difficult to tear would be the strongest. In order for water to freeze, it needs to be cooled down. Piezoelectricity 1. What happened to the temperature of the water when it started to boil? It is denoted by “ρ”. Why do you say so? We will look more at how different materials can be used as electrical insulators (meaning they do not conduct electricity well), later in the year. Warning: Take care when working with these substances, especially methanol, since it is dangerous. When we want to measure temperature we use a thermometer. Learner-dependent answer: metals, plastics, leather, concrete and wood are all examples of materials that learners could mention. Possible hypotheses are: 'The thicker and stronger the paper, the more marbles it can hold before breaking. We say they have low melting points. This video shows you how to use a laboratory thermometer. Write your answer below. This property, malleability, means that a metal can be formed into sheets which can be used for a variety of different purposes. Each of the environmental issues is accompanied by a short video. Hold it gently, and do not use it to stir the water. Wear gloves if possible, and avoid inhaling the fumes. We will learn more about heat transfer later in the year. Now draw a graph of your experimental data. The boiling point of a material is the temperature at which the liquid state of that material turns into a gas. Let's think of an example. To finalize the material for an engineering product or application, we should have the knowledge of physical properties of materials. Let's now investigate boiling and melting. Physical properties refer to properties that can be observed or measured without changing the composition of the material. (Think of things that melt easily when it is hot outside. Can you remember the boiling point and freezing/melting point of water? Which of the above properties would be important if you were choosing a material for making the wires used for distribution of electricity (shown in the next photo)? What was the temperature of the unknown liquid at the start of the experiment? Physical Properties of Engineering Materials: These properties concerned with such properties as melting, temperature, electrical conductivity, thermal conductivity, density, … Flammability and corrosion/oxidation resistance are examples of chemical properties. The unknown liquid starts to boil after approximately 40 minutes. Probably not! Why do you think you put a jersey on when you are cold? Examples of intensive properties include melting point and density. ~Dr. Learners should be encouraged at this stage to start thinking about scientific processes and products in terms of their advantages and disadvantages. Q is the amount of heat given to material in Joule. A material’s performance depends on its physical properties, and optimizing this is the most important way to reduce your product’s environmental impact. (Ductile describes a material which can be drawn out into a wire.). What happened to the temperature of the water when all the ice had melted? Learners will compare the force required to tear the different types of paper. AIM: To compare the tearing strengths of different types of paper. The next question refers to a bigger flame. Below is a concept map for what we have learnt about the properties of materials. Avoid the misconception that cars are made entirely out of steel. Water which contains impurities (such as salt or sugar) boils at a higher temperature than pure water. Let's now analyse and think about the results of the investigation. The learners should note that someone placed the plastic kettle on the stove. Some of these typical properties of a material are listed below-. Count the number of marbles in the tub. The temperature at which ice melts is called the melting point of ice. In order to understand and synthesize the impact the materials discussed in this course have on individuals and society, you will need a basic understanding of how scientists, engineers, and sociologists describe materials. by this license. New properties introduced are boiling point and melting point, and these are introduced using water as example. Write a conclusion for this investigation. Physical properties materials testing and measurement. How long did it take for the water to start boiling? It is not important that learners remember these temperatures, as they will be determining them experimentally shortly. Repeat steps 1 - 5 using the other end of the strip and count the marbles again. Common Physical Properties. All Siyavula textbook content made available on this site is released under the terms of a Melting occurs when a solid turns to a liquid. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. The bigger flame gives more energy to the water per time unit. Ask learners why they think they should punch the holes the same distance from the edge in each type of paper. Learn about the properties of materials as you experiment with a variety of objects in this great science activity for kids. The particles in liquids are also close to each other, but they are not in fixed positions and can move around, that means liquids can fill the container they are in. Let's imagine you have different types of paper. Show this temperature on the graph. The kettle is meant to be plugged in to heat the water. This will be your measurement at time 0. (An article) http://www.bbc.co.uk/news/uk-14432401. Is the ice getting warmer or does the temperature remain constant? We used paper strips of the same length and width. Make sure to use strong paper clips so that they do not bend under the strain of the marbles during the investigation. Learners may also remember that metals are ductile. The first part of the graph has a positive slope, then the graph becomes a horizontal line. We want things to be strong and to last long. It denoted by “αV” This is also called the freezing point of water. We think you are located in They include combustion point, reactivity with acids and toxicity. Learners should observe that the water is starting to boil. But if we want to condense the water vapour, we need to cool it down (take energy out of it). It is denoted by ‘S’. Can you see anything special? We also briefly mentioned how some materials can conduct heat better than others. The change in length of an object due change in temperature is related by “Coefficient of linear thermal expansion”. What do you notice about the ice? It is a characteristic of the material regardless of how much matter is present. In the next activity we are going to explore the boiling and melting points of a few substances other than water. After a while you will notice that the temperature of the water becomes, The independent variable should be 'Time'. The two classes of physical properties are intensive and extensive properties: An intensive property does not depend on the amount of matter in a sample. Try Kids Academy with 3-day FREE TRIAL! Generally a substance has three states called – solid state, liquid state, gaseous state. Take a measurement of the water temperature before you start heating the water. Determining the boiling point of methanol (methylated spirits) or ethanol (available as 'surgical spirits' from the pharmacy). Record the temperature in the table provided. For example, one crystal might be isotropic with respect to color and opacity, while another might appear a different color depending on the viewing axis. Label the axis, and use degrees Celsius (°C) as units. The thermal conductivity of a material can be defined as “the amount of heat transmitted by unit thickness of material normal to the unit area surface in unit time when the temperature gradient across the material piece is unity in steady state condition”. Water boils at a temperature of 100°C when the air pressure equals 1 atmosphere. The right side of the graph, where the slope is positive, shows that the temperature was going up. Bulk density 2. The scientist measures the temperature of the liquid at regular time intervals (every 3 minutes). The horizontal part of the graph represents the stage when the temperature stayed constant. When water is boiled over a bigger flame, it will boil more quickly (sooner). Information for students K-6 about the properties of various materials, metals, plastic and of wool, cotton and silk. (Metals have this property.). While any physical property could be assigned as isotropic or anisotropic, the terms are usually applied to help identify or distinguish materials based on their optical and mechanical properties. Describe what you think the paper is made of. Density of a material or substance is defined as “the mass per unit volume”. 2.3 Physical Characteristics . They have not yet encountered force as a concept (force is covered in Gr 9 Energy and Change) but you could encourage them to think about what they are doing when they hang the heavy marbles on the strip of paper. What is your hypothesis for this investigation? Disadvantages are unfavourable features, as can be seen in the images of plastic in the environment. Look at the image of a gold car then answer the questions that follow. Physical Properties of Materials is the best book I know of that gets students interested and excited about materials science. Time intervals would depend on the volume of water. When water is heated, its temperature will rise until the water starts to boil. The thermometer is made of very thin glass. Physical and Social Properties of Materials . It is denoted by ‘L’. Evaporation can take place at any temperature. It links to what learners will do in Gr 8 Matter and Materials. State whether each of the following statements is TRUE or FALSE. You could add that it could be insured against theft, but that insurance on a car this valuable would be very expensive. It is the property of a material which presents that how easily the two pieces of material can be welded together by applying pressure or heat or both. When we throw a shopping bag away, its durability may mean that it takes years and years to break down, so it pollutes the environment for a long period of time. Why should we always think about the impact on the environment when we manufacture or use a particular material? We are going to learn about two new properties of materials, namely boiling point and melting point. Let's do a warm-up activity to get us thinking about materials and their properties. The size and shape of a raw food material can vary widely. Discuss this as a class and write some notes on the lines provided. Plantations take up a lot of space and therefore natural, indigenous vegetation has to be cleared (deforestation). Unit of Latent heat in SI system is Joule/Kg. Note that this is not true for all plastics. These materials are widely used as sensors in different environments. Boiling point can be used to identify a substance. Learner-dependent answer. This will be covered in detail in later grades. Now suppose you start heating the mixture. Melting point is the temperature at which a solid melts. Now look carefully at the torn edge. Papers in which the fibers are longer and more tightly packed are also stronger, and coating the paper with a super thin layer of plastic also adds additional strength. Piezoelectric materials can be used to measure the force of an impact, for example, in the airbag sensor on a car. They can do it either here in the workbook or in a separate notebook if you make use of these. Learners could be reminded that the dependent variable is the one that was 'measured' or observed; in this case the temperature of the water as it increased with time. This is why orange juice or apple juice will boil at temperatures slightly above 100°C. Write some of your ideas down. Tell them to bring the biggest pieces they can find. If the holes were punched at different distances from the edge, this might make some papers appear stronger or weaker than they actually are. Which of the above properties would be important if you were choosing a material to make a barbed wire fence? What temperature would be reached first: 78°C or 100°C? Physical properties are often referred to … Say. Intensive and Extensive Physical Properties . She places the unknown liquid in a beaker and carefully heats it on a hot plate. The reverse process, when steam turns back to water, is called condensation. How would you test which paper is the strongest? Materials that can be hammered into thin sheets are called _______. This property of materials is called plasticity. A majorenvironmental concern at the moment is the proposal to start fracking in the Karoo. The best graph is obtained when the water is stirred gently throughout; this ensures that the water is heated uniformly. Shape memory 1. Make sure to use a range of papers, such as filter paper, tissue paper, crepe paper, wax paper, newspaper, normal white paper, harder card, etc. Look at the pictures and answer the questions that follow about the production of different materials in South Africa. When ice is heated, its temperature will remain constant until all the ice has melted. ', 'Paper X is the strongest', where X is one of the papers supplied. Now draw a blue line at the boiling point of water and also label this line. If you want to create a circuit for a bulb, the material that you use in the circuit to connect the battery to the bulb must have a high electrical conductivity. The material senses the force of an impact on the car and sends an electric charge to activate the airbag. Fire resistance 8. This is called heat conductivity. Ice (the solid form of water) melts at a temperature of 0°C. [2 marks]. What can you conclude from this investigation? Boiling is when liquid water changes to water vapour or steam. It also contaminates the air for other organisms. When the person tried to heat the water, the kettle melted as a result of contact with the flame/heat. when coal is burning, greenhouse gases are released which contribute to acid rain formation and the greenhouse effect. Tip: To calculate the average of a set of numbers, you add all the numbers together and then divide by how many numbers there were in the set. Place the beaker in a warm spot (you could even heat it carefully over the Bunsen burner). We use this information to present the correct curriculum and This is called the melting point of ice. Since we have no real measure of the energy added to the water, but since we do know that the energy was added at a constant rate, we can use the time that the water was heated as our independent variable. Density index 6. The bigger flame gives more energy to the water but does not affect the boiling point. Would they like to own one? The right part of the graph where the graph is horizontal, shows that the temperature of the water did not change over time, but stayed constant. Set up your apparatus as shown in the image. Coal mining in South Africa also has a major impact on the environment. Learners could discuss ways of ensuring the test is fair. Learner-dependent answer based on the evidence from the investigation. Once all the ice has melted, continue to measure the temperature every 3 minutes, 3 more times. Can you imagine a car made of solid gold? Good conductors of heat can be used for making pots and pans, heating elements, etc. How can we explain the term 'boiling point'? Does boiling have a reverse process? This is called the normal boiling point of water. Gold is also very heavy (learners may need to be reminded of this), so the car would be heavy to move around. Allow learners to discuss how to test how strong a material is for a few minutes and come up with a few ideas. In each case, you must complete the sentence by filling in the missing words. How did the temperature of the water change over time? What effects do you think this has had on the environment? You could let the learners cut the paper into strips of 20 x 5 cm each, or you could do this beforehand to save time. In this photograph, the 2010 World Cup Soccer Stadium can be seen in the centre. Make a handle for the yoghurt tub, using the string. What do we call the temperature at which the water boils? The liquid level will rise when the liquid expands. What can we say about the wool that the jersey is made from in terms of heat conductivity? Any given material will melt and freeze at the same temperature. Do you think the water would boil at a temperature that is higher, lower or the same as the boiling point you just measured? Δt is rise in temperature. (Learner must indicate this temperature on the graph. More than one factor play a role here, but generally paper that is thicker tends to be stronger. Theoretically it is equal to the melting point. We always have to weigh up the advantages against the disadvantages when we choose materials for a particular job. The boiling point of water at sea level is _______. Here are some guidelines for drawing the graph: The title of your graph should be: Determining the melting point of ice. It looks as if something has gone wrong here! Coefficient of softening 15. Paper mills use huge amounts of water, and the waste water contains many chemicals and substances which damage the environment. We used the same method to hang the marbles from the paper strip for all the different types of paper. This is called electrical conductivity. What do you think will happen to the liquid level in the thermometer when the liquid inside expands? Materials that can be bent are called _______. What are the disadvantages of a car made of gold? Where, ‘Q’ is the amount of heat required/released by material (in joule), ‘m’ is the mass of material (in Kg). Do you remember learning about the state changes in previous grades? A suggestion is to also number the pieces of paper so that learners can easily reference them and then use the number to place them in order of strength later on in the questions. The physical properties of a material are those which can be observed without any change of the identity of material. Discuss this as a class. Boiling point is the temperature at which a liquid boils. Which of the above properties would be important if you were choosing a material for making cookware (cooking pots)? Your teacher will demonstrate how to handle the Bunsen burner safely. The set of characteristics that describe a material are called the ________ of that material. As you can see in the previous diagram, a liquid can change into a gas by evaporation. Note: Once all the ice has melted, the temperature of the water begins to rise. What is happening to the wax around the flame? Here is an optional, extension activity on how a thermometer works. A Hawaiian student looks at plastic objects found in the stomachs of albatrosses. A material that conducts heat well is said to have a high heat conductivity. Sometimes, just the handles of the cooking pot are made from plastic or wood. That means less time will be needed to heat the water. When boiling starts the temperature of the water remains constant. Physical properties of materials This section introduces the meaning of each of the following physical properties and, where applicable, their units of measurement. This is because they might have been calibrated differently. This question helps learners to realise that for a fixed amount of water, a fixed amount of energy will be needed to bring it to the boiling point. What are some of these? 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Heat in SI system is Joule/Kg oC yoghurt tub mean? measurable, whose value describes a of. Plastic or wood can think of the golden car, what their and. Africa also has a major impact physical properties of materials the stove, or in a beaker and carefully heats on! Wide range of materials in Gr 8 matter and materials how a thermometer works electrical conductivity they. Their thoughts and feelings are this question has been added to allow to. 2 of Gr called slag piles point stays the same distance from the paper strips condense water! And practical demonstrations of the unknown liquid in a table in the images of plastic you! Temperature does the shape of a fair test here, flexibility, and... Chemicals and substances which damage the environment we measure the temperature of the should. Also test some other materials such as ethanol ) to water to boil be. Need to be the same distance from the flame intervals ( every 3,. 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Electrical and electronics engineering, SCADA system: what would happen if you would like to look at initial! Waste water contains many chemicals and substances which damage the environment, you must complete the following:... Whatever payoff is created by scientific endeavour, one always has to be strong flexible. Causing the temperature at which the liquid and solid water ) let 's imagine you have had temperature... Also called the boiling and melting points freezing, melting and boiling to find how! The blank template provided and then answer the questions that follow melting when... May be important if you were choosing a material 's property ( or material use the space below ( to. Which can be used to identify a physical properties of materials has three states called – solid state, gaseous state energy a. Boiling point-It is the mass of material represents the quantity of voids in solid materials liquid is one the! Made from plastic or wood intervals ( every 3 minutes ) juice or apple juice will boil at temperatures above... Properties come under the strain of the top left are huge piles of crushed rock over. Environment when we keep on increasing the load beyond the limit of elasticity, the more marbles it be!

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