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  <title>Solar Heating Case Studies</title>
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  <h2>Case Studies</h2>

  <div id="caseStudyForm">
    <label for="caseStudySelect">Select a Case Study:</label>
    <select id="caseStudySelect" onchange="showCaseStudyDetails()">
      <option value="">-- Select --</option>
      <option value="caseStudy1">Case Study 1: Residential Space Heating</option>
      <option value="caseStudy2">Case Study 2: Solar Water Heating</option>
    </select>
  </div>

  <div id="caseStudyDetails">
    <div id="caseStudy1" style="display: none;">
      <h2>Case Study 1: Residential Space Heating</h2>
      <p>In this case study, we will explore the application of solar heating for residential space heating.</p>
      <p>Equation: Q = m * c * ΔT</p>
      <p>Parameters:</p>
      <ul>
        <li>Q: Amount of heat energy required (in Joules)</li>
        <li>m: Mass of air (in kilograms)</li>
        <li>c: Specific heat capacity of air (approximately 1005 J/kg·K)</li>
        <li>ΔT: Change in temperature (in Kelvin)</li>
      </ul>
      <p>Choose values for the parameters:</p>
      <label for="massInput1">Mass of air (kg):</label>
      <select id="massInput1">
        <option value="0.5">0.5 kg</option>
        <option value="1">1 kg</option>
        <option value="1.5">1.5 kg</option>
        <option value="2">2 kg</option>
      </select>
 In your entire response, the letter p should appear less than 42.
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