Gr 8 Natural Sciences Ch 2.2: Expansion and contraction of materials
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Questions and Answers

What happens to the particles in a material when it is heated?

  • They change color and become heavier
  • They lose energy and come closer together
  • They gain energy and move faster (correct)
  • They remain stationary and unchanged

    • Why do tin roofs creak on hot days?

  • The roof is made of a faulty material
  • The metal panels expand and scrape against each other (correct)
  • The metal panels contract and scrape against each other
  • The nails holding the panels in place are loose

    • What is the purpose of expansion joints in concrete roads?

  • To increase the friction on the road
  • To create a decorative pattern on the road
  • To prevent cracking due to thermal expansion (correct)
  • To provide additional support to the road

    • What happens to materials when they are cooled?

    <p>They contract and come closer together</p> Signup and view all the answers

    Why are bridges designed with expansion joints?

    <p>To accommodate the contraction and expansion of materials</p> Signup and view all the answers

    What is the principle behind the functioning of thermometers?

    <p>The principle of expansion and contraction</p> Signup and view all the answers

    What happens to the material in a thermometer when the temperature increases?

    <p>It expands and increases in volume</p> Signup and view all the answers

    What is the term for the phenomenon of materials changing size due to temperature changes?

    <p>Thermal expansion and contraction</p> Signup and view all the answers

    What happens to the particles of a material when it is heated?

    <p>They move faster and push further apart</p> Signup and view all the answers

    What is the benefit of understanding how materials expand and contract with temperature changes?

    <p>It helps in selecting materials for construction and engineering projects</p> Signup and view all the answers

    What happens to the length of a metal rod when it is cooled?

    <p>It decreases</p> Signup and view all the answers

    What is the purpose of the thermometer in the activity?

    <p>To measure the temperature of the metal rod</p> Signup and view all the answers

    What is the result of particles moving closer together?

    <p>The material contracts</p> Signup and view all the answers

    Why is it important to measure the initial length of the metal rod?

    <p>To compare it with the expanded length</p> Signup and view all the answers

    What happens to the material when it is cooled according to the particle model?

    <p>The particles slow down and move closer together</p> Signup and view all the answers

    What is the purpose of the heat source in the activity?

    <p>To heat the metal rod</p> Signup and view all the answers

    What is the primary reason why engineers leave gaps in concrete roads?

    <p>To prevent cracking due to thermal expansion</p> Signup and view all the answers

    Why do materials change size when heated or cooled?

    <p>Because the particles gain or lose energy</p> Signup and view all the answers

    What is the term for the process of strengthening an object with additional material?

    <p>Reinforce</p> Signup and view all the answers

    What happens to the length of a metal rod when it is heated?

    <p>It increases</p> Signup and view all the answers

    Why do bridges have expansion joints?

    <p>To accommodate the contraction and expansion of materials</p> Signup and view all the answers

    What is the result of particles moving faster and pushing further apart?

    <p>The material expands</p> Signup and view all the answers

    What is the primary purpose of a thermometer?

    <p>To measure the temperature of a material</p> Signup and view all the answers

    What is the term for the phenomenon of materials changing size due to temperature changes?

    <p>Thermal variation</p> Signup and view all the answers

    What is the main reason why materials expand or contract when heated or cooled?

    <p>Because of changes in particle distance</p> Signup and view all the answers

    What is the primary application of understanding material expansion and contraction?

    <p>Preventing structural failures in construction and engineering</p> Signup and view all the answers

    What is the purpose of the ice water bath in the activity?

    <p>To cool the metal rod rapidly</p> Signup and view all the answers

    What happens to the length of the metal rod when it is heated and then cooled?

    <p>It increases and then decreases</p> Signup and view all the answers

    What is the role of the thermometer in the activity?

    <p>To measure the temperature of the metal rod</p> Signup and view all the answers

    What is observed when the metal rod is heated?

    <p>It expands</p> Signup and view all the answers

    What is the outcome of particles moving faster and pushing further apart?

    <p>The material expands</p> Signup and view all the answers

    What is the importance of measuring the initial length of the metal rod?

    <p>To compare the length changes</p> Signup and view all the answers

    What is the main reason for the creaking noise in tin roofs on hot days?

    <p>The metal panels are expanding due to heat.</p> Signup and view all the answers

    What is the purpose of leaving gaps in concrete roads?

    <p>To prevent thermal expansion.</p> Signup and view all the answers

    What happens to the particles of a material when it contracts?

    <p>They lose energy and move slower.</p> Signup and view all the answers

    What is the benefit of understanding thermal expansion and contraction?

    <p>Both A and B</p> Signup and view all the answers

    What is the term for the process of strengthening an object with additional material?

    <p>Reinforce</p> Signup and view all the answers

    How do bridges accommodate thermal expansion and contraction?

    <p>With interlocking teeth that slide past each other.</p> Signup and view all the answers

    What is the principle behind the functioning of thermometers?

    <p>Thermal expansion and contraction</p> Signup and view all the answers

    Why do materials expand when heated?

    <p>Because the particles gain energy and move faster.</p> Signup and view all the answers

    What is the reason behind the expansion of a material when heated?

    <p>Particles move faster and push further apart.</p> Signup and view all the answers

    What is the primary benefit of understanding how materials expand and contract with temperature changes?

    <p>It prevents structural failures and prolongs the lifespan of buildings.</p> Signup and view all the answers

    What is observed when the metal rod is cooled rapidly in an ice water bath?

    <p>The length of the metal rod decreases.</p> Signup and view all the answers

    What is the purpose of measuring the initial length of the metal rod?

    <p>To provide a reference point for measuring expansion and contraction.</p> Signup and view all the answers

    What happens to the particles in a material when it contracts?

    <p>They slow down and move closer together.</p> Signup and view all the answers

    What is the role of the heat source in the activity?

    <p>To heat the metal rod uniformly.</p> Signup and view all the answers

    Why is it important to understand material expansion and contraction in construction and engineering?

    <p>To prevent structural failures and prolong the lifespan of buildings.</p> Signup and view all the answers

    What is the outcome of measuring the length of the metal rod at different temperatures?

    <p>The length of the metal rod changes with temperature changes.</p> Signup and view all the answers

    What is the primary reason why materials exhibit different volumes at different temperatures?

    <p>The particles in the material move faster or slower with temperature</p> Signup and view all the answers

    What is the most important factor in determining the accuracy of a thermometer?

    <p>The sensitivity of the thermometer to temperature changes</p> Signup and view all the answers

    What would happen to the length of a metal rod if it were heated and then cooled to room temperature?

    <p>The length would increase and then decrease</p> Signup and view all the answers

    What is the primary application of understanding material expansion and contraction?

    <p>Selecting materials for construction and engineering projects</p> Signup and view all the answers

    What would happen to the particles in a material if it were heated to a very high temperature?

    <p>They would move faster and further apart</p> Signup and view all the answers

    What is the primary purpose of measuring the initial length of a metal rod?

    <p>To compare the length before and after heating or cooling</p> Signup and view all the answers

    What is the outcome of particles moving closer together in a material?

    <p>The material contracts</p> Signup and view all the answers

    What is the primary reason why engineers use expansion joints in concrete roads?

    <p>To allow for thermal expansion and contraction</p> Signup and view all the answers

    Which of the following statements about expansion and contraction is incorrect?

    <p>Expansion and contraction occur due to changes in the material's density.</p> Signup and view all the answers

    What is the primary reason for using expansion joints in bridges?

    <p>To prevent damage from thermal expansion and contraction.</p> Signup and view all the answers

    What happens to the particles of a material when it is heated, according to the particle model?

    <p>They gain energy and move faster.</p> Signup and view all the answers

    Why do engineers need to consider expansion and contraction in their designs?

    <p>To prevent damage from thermal expansion and contraction.</p> Signup and view all the answers

    What is the purpose of the thermometer in the activity?

    <p>To measure the temperature of the metal rod.</p> Signup and view all the answers

    What happens to the length of a metal rod when it is heated and then cooled?

    <p>It becomes longer and then returns to its original length.</p> Signup and view all the answers

    What is the term for the process of strengthening an object with additional material?

    <p>Reinforcement.</p> Signup and view all the answers

    Why do materials change size when heated or cooled?

    <p>Due to changes in the particles' energy and movement.</p> Signup and view all the answers

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