<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 10px 12px 14px;
      user-select: none;
    }

    .diagram-area {
      position: relative;
      width: 100%;
      max-width: 440px;
      height: 320px;
      display: flex;
      justify-content: center;
      align-items: center;
    }

    svg {
      width: 100%;
      height: 100%;
      overflow: visible;
    }

    /* Flow Animations */
    .flow-line {
      fill: none;
      stroke-width: 4.5;
      stroke-linecap: round;
      stroke-dasharray: 10 14;
      animation: circulate 3.6s linear infinite;
    }

    .flow-left {
      stroke: url(#leftLoopGrad);
    }

    .flow-right {
      stroke: url(#rightLoopGrad);
    }

    @keyframes circulate {
      to {
        stroke-dashoffset: -48;
      }
    }

    /* Flame Animation */
    .flame-core {
      animation: flicker 1.2s ease-in-out infinite alternate;
      transform-origin: 200px 290px;
    }
    .flame-glow {
      animation: glow 1.2s ease-in-out infinite alternate;
      transform-origin: 200px 290px;
    }

    @keyframes flicker {
      0% { transform: scale(0.96, 0.94); opacity: 0.9; }
      100% { transform: scale(1.04, 1.08); opacity: 1; }
    }
    @keyframes glow {
      0% { opacity: 0.25; transform: scale(0.92); }
      100% { opacity: 0.45; transform: scale(1.1); }
    }

    /* Floating informative badges */
    .badge {
      position: absolute;
      font-size: 11.5px;
      font-weight: 700;
      padding: 4px 8px;
      border-radius: 6px;
      line-height: 1.25;
      text-align: center;
      box-shadow: 0 1px 4px rgba(0,0,0,0.06);
      pointer-events: none;
    }

    .badge-rise {
      top: 34%;
      left: 50%;
      transform: translate(-50%, -50%);
      background: #fff1f2;
      color: #e11d48;
      border: 1px solid #fecdd3;
    }

    .badge-sink-left {
      top: 40%;
      left: 7%;
      background: #eff6ff;
      color: #1d4ed8;
      border: 1px solid #bfdbfe;
    }

    .badge-sink-right {
      top: 40%;
      right: 7%;
      background: #eff6ff;
      color: #1d4ed8;
      border: 1px solid #bfdbfe;
    }

    /* Controls bar */
    .controls {
      display: flex;
      align-items: center;
      gap: 10px;
      margin-top: 4px;
    }

    .btn {
      appearance: none;
      border: 1px solid #e2e8f0;
      background: #f8fafc;
      color: #1e2945;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 14px;
      border-radius: 8px;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      transition: background 0.15s, border-color 0.15s;
    }

    .btn:active {
      background: #e2e8f0;
    }

    .title-pill {
      font-size: 13px;
      font-weight: 700;
      color: #0f172a;
      background: #f1f5f9;
      padding: 4px 12px;
      border-radius: 12px;
      letter-spacing: 0.3px;
    }
  </style>
</head>
<body>

  <div class="title-pill">Convection Current</div>

  <div class="diagram-area">
    <svg viewBox="0 0 400 310">
      <defs>
        
        <linearGradient id="leftLoopGrad" x1="100%" y1="100%" x2="0%" y2="0%">
          <stop offset="0%" stop-color="#ef4444" />
          <stop offset="35%" stop-color="#f97316" />
          <stop offset="70%" stop-color="#3b82f6" />
          <stop offset="100%" stop-color="#2563eb" />
        </linearGradient>

        <linearGradient id="rightLoopGrad" x1="0%" y1="100%" x2="100%" y2="0%">
          <stop offset="0%" stop-color="#ef4444" />
          <stop offset="35%" stop-color="#f97316" />
          <stop offset="70%" stop-color="#3b82f6" />
          <stop offset="100%" stop-color="#2563eb" />
        </linearGradient>

        
        <linearGradient id="waterGrad" x1="0%" y1="100%" x2="0%" y2="0%">
          <stop offset="0%" stop-color="#fef2f2" />
          <stop offset="30%" stop-color="#e0f2fe" />
          <stop offset="100%" stop-color="#f0f9ff" />
        </linearGradient>

        <radialGradient id="heatGlow" cx="50%" cy="50%" r="50%">
          <stop offset="0%" stop-color="#fb923c" stop-opacity="0.8" />
          <stop offset="100%" stop-color="#ea580c" stop-opacity="0" />
        </radialGradient>
      </defs>

      
      <path d="M 120 280 L 280 280 M 135 280 L 125 305 M 265 280 L 275 305" stroke="#94a3b8" stroke-width="3" stroke-linecap="round" />
      <rect x="188" y="292" width="24" height="13" rx="2" fill="#64748b" />
      <line x1="200" y1="286" x2="200" y2="292" stroke="#475569" stroke-width="4" />

      
      <g id="flameGroup">
        <circle class="flame-glow" cx="200" cy="275" r="22" fill="url(#heatGlow)" />
        
        <path class="flame-core" d="M 200 258 Q 208 270 207 278 Q 205 285 200 285 Q 195 285 193 278 Q 192 270 200 258 Z" fill="#f97316" />
        
        <path class="flame-core" d="M 200 265 Q 204 273 203 280 Q 202 284 200 284 Q 198 284 197 280 Q 196 273 200 265 Z" fill="#fef08a" />
      </g>

      
      <rect x="85" y="45" width="230" height="210" rx="10" fill="url(#waterGrad)" />
      
      
      <path d="M 85 55 Q 142 52 200 55 T 315 55" fill="none" stroke="#38bdf8" stroke-width="2.5" opacity="0.7" />

      
      <path d="M 80 35 L 85 45 L 85 245 A 10 10 0 0 0 95 255 L 305 255 A 10 10 0 0 0 315 245 L 315 45 L 320 35" fill="none" stroke="#64748b" stroke-width="3.5" stroke-linecap="round" />
      
      
      <line x1="86" y1="95" x2="100" y2="95" stroke="#94a3b8" stroke-width="1.5" />
      <line x1="86" y1="140" x2="106" y2="140" stroke="#94a3b8" stroke-width="1.5" />
      <line x1="86" y1="185" x2="100" y2="185" stroke="#94a3b8" stroke-width="1.5" />
      <line x1="86" y1="230" x2="106" y2="230" stroke="#94a3b8" stroke-width="1.5" />

      
      
      <path id="pathLeft" class="flow-line flow-left"
        d="M 194 238
           C 188 170, 185 100, 170 72
           C 155 58, 125 58, 114 74
           C 102 92, 104 185, 114 225
           C 122 244, 160 244, 194 238" />

      
      <path id="pathRight" class="flow-line flow-right"
        d="M 206 238
           C 212 170, 215 100, 230 72
           C 245 58, 275 58, 286 74
           C 298 92, 296 185, 286 225
           C 278 244, 240 244, 206 238" />

      
      
      <polygon points="190,140 184,152 196,152" fill="#ef4444" />
      <polygon points="210,140 204,152 216,152" fill="#ef4444" />

      
      <polygon points="108,160 102,148 114,148" fill="#2563eb" />
      <polygon points="292,160 286,148 298,148" fill="#2563eb" />

      
      <polygon points="160,242 148,237 150,247" fill="#ea580c" />
      <polygon points="240,242 250,247 252,237" fill="#ea580c" />

    </svg>

    
    <div class="badge badge-rise">Warm, less dense<br>water rises</div>
    <div class="badge badge-sink-left">Cooler, denser<br>water sinks</div>
    <div class="badge badge-sink-right">Cooler, denser<br>water sinks</div>
  </div>

  <div class="controls">
    <button id="toggleBtn" class="btn" onclick="toggleFlow()">
      <span id="btnIcon">⏸</span>
      <span id="btnText">Pause Flow</span>
    </button>
  </div>

  <script>
    let isFlowing = true;
    const lines = document.querySelectorAll('.flow-line');
    const flame = document.getElementById('flameGroup');
    const btnIcon = document.getElementById('btnIcon');
    const btnText = document.getElementById('btnText');

    function toggleFlow() {
      isFlowing = !isFlowing;
      lines.forEach(line => {
        line.style.animationPlayState = isFlowing ? 'running' : 'paused';
      });
      flame.style.opacity = isFlowing ? '1' : '0.2';
      btnIcon.textContent = isFlowing ? '⏸' : '▶';
      btnText.textContent = isFlowing ? 'Pause Flow' : 'Heat & Flow';
    }
  </script>
</body>
</html>

Thermal Conduction, Convection, and Radiation Mechanisms

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: #f8fafc;
      color: #1e293b;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 10px;
      user-select: none;
    }

    .controls {
      display: flex;
      gap: 6px;
      margin-bottom: 6px;
      flex-wrap: wrap;
      justify-content: center;
      z-index: 10;
    }

    .btn {
      appearance: none;
      border: 1px solid #cbd5e1;
      background: #ffffff;
      color: #475569;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 12px;
      border-radius: 20px;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 5px;
      transition: all 0.25s ease;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }
    .btn:hover { background: #f1f5f9; }
    .btn.active {
      background: #0f172a;
      color: #ffffff;
      border-color: #0f172a;
    }
    .btn.active[data-target="convection"] { background: #2563eb; border-color: #2563eb; }
    .btn.active[data-target="conduction"] { background: #059669; border-color: #059669; }
    .btn.active[data-target="radiation"] { background: #ea580c; border-color: #ea580c; }

    .svg-container {
      width: 100%;
      max-width: 600px;
      position: relative;
      flex: 1;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    svg {
      width: 100%;
      height: auto;
      overflow: visible;
    }

    .mech-group {
      transition: opacity 0.35s ease, filter 0.35s ease;
    }
    .mech-group.dimmed {
      opacity: 0.18;
      filter: grayscale(80%);
    }

    /* Animation effects */
    @keyframes riseLoop {
      0% { stroke-dashoffset: 48; }
      100% { stroke-dashoffset: 0; }
    }
    .rising-path {
      stroke-dasharray: 6 6;
      animation: riseLoop 1.8s linear infinite;
    }

    @keyframes radiateWave {
      0% { stroke-dashoffset: 40; opacity: 0.3; }
      50% { opacity: 1; }
      100% { stroke-dashoffset: 0; opacity: 0.3; }
    }
    .radiation-ray {
      stroke-dasharray: 8 4;
      animation: radiateWave 1.4s linear infinite;
    }

    @keyframes heatFlow {
      0% { stroke-dashoffset: 32; }
      100% { stroke-dashoffset: 0; }
    }
    .heat-arrow {
      stroke-dasharray: 8 4;
      animation: heatFlow 1.2s linear infinite;
    }

    @keyframes flameFlicker {
      0%, 100% { transform: scale(1) translateY(0); }
      50% { transform: scale(1.04, 0.96) translateY(-2px); }
    }
    .flame-core {
      transform-origin: 290px 340px;
      animation: flameFlicker 1s ease-in-out infinite alternate;
    }
  </style>
</head>
<body>

  
  <div class="controls">
    <button class="btn active" data-target="all">All</button>
    <button class="btn" data-target="conduction">● Conduction</button>
    <button class="btn" data-target="convection">● Convection</button>
    <button class="btn" data-target="radiation">● Radiation</button>
  </div>

  <div class="svg-container">
    <svg viewBox="0 0 600 420" xmlns="http://www.w3.org/2000/svg">
      <defs>
        
        <marker id="arr-convection" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
          <path d="M0,0 L6,3 L0,6 Z" fill="#2563eb" />
        </marker>
        <marker id="arr-conduction" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
          <path d="M0,0 L6,3 L0,6 Z" fill="#059669" />
        </marker>
        <marker id="arr-radiation" markerWidth="6" markerHeight="6" refX="4" refY="3" orient="auto">
          <path d="M0,0 L6,3 L0,6 Z" fill="#ea580c" />
        </marker>

        
        <linearGradient id="rodGrad" x1="100%" y1="100%" x2="0%" y2="0%">
          <stop offset="0%" stop-color="#ef4444" />
          <stop offset="40%" stop-color="#f97316" />
          <stop offset="75%" stop-color="#94a3b8" />
          <stop offset="100%" stop-color="#475569" />
        </linearGradient>

        <linearGradient id="fireGrad" x1="0" y1="1" x2="0" y2="0">
          <stop offset="0%" stop-color="#ea580c" />
          <stop offset="60%" stop-color="#f59e0b" />
          <stop offset="100%" stop-color="#fef08a" />
        </linearGradient>

        <radialGradient id="fireGlow" cx="50%" cy="50%" r="50%">
          <stop offset="0%" stop-color="#f97316" stop-opacity="0.35" />
          <stop offset="100%" stop-color="#f97316" stop-opacity="0" />
        </radialGradient>
      </defs>

      
      <circle cx="290" cy="310" r="130" fill="url(#fireGlow)" />

      
      <ellipse cx="300" cy="380" rx="270" ry="24" fill="#e2e8f0" />

      
      <g id="grp-convection" class="mech-group">
        
        <path class="rising-path" d="M 290 240 Q 290 140 290 70" fill="none" stroke="#2563eb" stroke-width="3" marker-end="url(#arr-convection)" />
        <path class="rising-path" d="M 270 250 Q 240 160 250 85" fill="none" stroke="#3b82f6" stroke-width="2.5" marker-end="url(#arr-convection)" />
        <path class="rising-path" d="M 310 250 Q 340 160 330 85" fill="none" stroke="#3b82f6" stroke-width="2.5" marker-end="url(#arr-convection)" />
        
        
        <path class="rising-path" d="M 240 120 C 200 130 200 190 230 210" fill="none" stroke="#60a5fa" stroke-width="1.8" stroke-dasharray="4 4" marker-end="url(#arr-convection)" />
        <path class="rising-path" d="M 340 120 C 380 130 380 190 350 210" fill="none" stroke="#60a5fa" stroke-width="1.8" stroke-dasharray="4 4" marker-end="url(#arr-convection)" />

        
        <g transform="translate(290, 40)">
          <rect x="-60" y="-14" width="120" height="28" rx="14" fill="#2563eb" />
          <text x="0" y="4" fill="#ffffff" font-size="13" font-weight="700" text-anchor="middle">Convection</text>
        </g>
      </g>

      
      <g id="grp-conduction" class="mech-group">
        
        <line x1="280" y1="320" x2="80" y2="180" stroke="url(#rodGrad)" stroke-width="7" stroke-linecap="round" />
        
        <line class="heat-arrow" x1="260" y1="305" x2="110" y2="200" stroke="#059669" stroke-width="3.5" marker-end="url(#arr-conduction)" />
        
        
        <rect x="250" y="290" width="18" height="15" rx="4" transform="rotate(35 250 290)" fill="#fef3c7" stroke="#d97706" stroke-width="1.5" />

        
        <rect x="65" y="165" width="30" height="16" rx="4" fill="#78350f" transform="rotate(35 65 165)" />
        <text x="50" y="165" font-size="28">✊</text>

        
        <g transform="translate(100, 125)">
          <rect x="-56" y="-14" width="112" height="28" rx="14" fill="#059669" />
          <text x="0" y="4" fill="#ffffff" font-size="13" font-weight="700" text-anchor="middle">Conduction</text>
        </g>
      </g>

      
      <g id="fire-base">
        
        <rect x="235" y="340" width="110" height="18" rx="5" transform="rotate(18 290 350)" fill="#78350f" stroke="#451a03" stroke-width="2" />
        <rect x="235" y="340" width="110" height="18" rx="5" transform="rotate(-18 290 350)" fill="#92400e" stroke="#451a03" stroke-width="2" />
        
        
        <g class="flame-core">
          <path d="M 290 230 Q 320 280 325 330 Q 290 360 255 330 Q 260 280 290 230 Z" fill="url(#fireGrad)" />
          <path d="M 290 260 Q 308 295 310 330 Q 290 350 270 330 Q 272 295 290 260 Z" fill="#fef08a" />
        </g>
      </g>

      
      <g id="grp-radiation" class="mech-group">
        
        <path class="radiation-ray" d="M 330 300 Q 370 285 410 300 T 480 295" fill="none" stroke="#ea580c" stroke-width="3" marker-end="url(#arr-radiation)" />
        <path class="radiation-ray" d="M 335 320 Q 375 305 415 320 T 480 315" fill="none" stroke="#f97316" stroke-width="3" marker-end="url(#arr-radiation)" />
        <path class="radiation-ray" d="M 330 340 Q 370 325 410 340 T 480 335" fill="none" stroke="#ea580c" stroke-width="3" marker-end="url(#arr-radiation)" />

        
        <text x="500" y="325" font-size="44" transform="scale(-1, 1) translate(-1040, 0)">🤲</text>

        
        <g transform="translate(485, 235)">
          <rect x="-52" y="-14" width="104" height="28" rx="14" fill="#ea580c" />
          <text x="0" y="4" fill="#ffffff" font-size="13" font-weight="700" text-anchor="middle">Radiation</text>
        </g>
      </g>
    </svg>
  </div>

  <script>
    const buttons = document.querySelectorAll('.btn');
    const groups = {
      convection: document.getElementById('grp-convection'),
      conduction: document.getElementById('grp-conduction'),
      radiation: document.getElementById('grp-radiation')
    };

    buttons.forEach(btn => {
      btn.addEventListener('click', () => {
        buttons.forEach(b => b.classList.remove('active'));
        btn.classList.add('active');

        const target = btn.getAttribute('data-target');

        Object.keys(groups).forEach(key => {
          if (target === 'all' || target === key) {
            groups[key].classList.remove('dimmed');
          } else {
            groups[key].classList.add('dimmed');
          }
        });
      });
    });
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: transparent;
      color: #0f172a;
      padding: 12px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      min-height: 100%;
    }

    .grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 12px;
      width: 100%;
      max-width: 680px;
      margin: 0 auto;
    }

    .column-card {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      border-radius: 10px;
      padding: 12px 10px;
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      box-shadow: 0 1px 4px rgba(0,0,0,0.05);
    }

    .title {
      font-size: 15px;
      font-weight: 700;
      color: #0f172a;
      margin-bottom: 8px;
    }

    .scene-box {
      width: 100%;
      height: 96px;
      background: #f8fafc;
      border-radius: 8px;
      margin-bottom: 10px;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
      overflow: hidden;
      border: 1px solid #e2e8f0;
    }

    .badge-group {
      display: flex;
      flex-direction: column;
      gap: 6px;
      width: 100%;
    }

    .badge-item {
      display: flex;
      flex-direction: column;
      gap: 2px;
    }

    .badge-label {
      font-size: 10px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.5px;
      color: #475569;
    }

    .badge {
      font-size: 11.5px;
      font-weight: 600;
      padding: 4px 6px;
      border-radius: 6px;
      line-height: 1.25;
    }

    .badge-medium {
      background: #e2e8f0;
      color: #0f172a;
      border: 1px solid #cbd5e1;
    }

    .badge-flow-no {
      background: #fee2e2;
      color: #7f1d1d;
      border: 1px solid #fecaca;
    }

    .badge-flow-yes {
      background: #dcfce7;
      color: #14532d;
      border: 1px solid #bbf7d0;
    }

    /* Conduction animations: calmed to >=500ms */
    @keyframes vibrate1 {
      0%, 100% { transform: translate(0, 0); }
      25% { transform: translate(-2px, 1.5px); }
      75% { transform: translate(2px, -1.5px); }
    }
    @keyframes vibrate2 {
      0%, 100% { transform: translate(0, 0); }
      25% { transform: translate(1.5px, -1px); }
      75% { transform: translate(-1.5px, 1px); }
    }
    @keyframes vibrate3 {
      0%, 100% { transform: translate(0, 0); }
      25% { transform: translate(-1px, 0.8px); }
      75% { transform: translate(1px, -0.8px); }
    }

    .atom-hot { animation: vibrate1 0.6s infinite ease-in-out; }
    .atom-mid { animation: vibrate2 0.85s infinite ease-in-out; }
    .atom-cool { animation: vibrate3 1.2s infinite ease-in-out; }

    /* Convection animations */
    @keyframes fluidCycle {
      0% { stroke-dashoffset: 0; }
      100% { stroke-dashoffset: -48; }
    }
    .flow-path {
      stroke-dasharray: 6, 6;
      animation: fluidCycle 2.4s linear infinite;
    }

    /* Radiation animations */
    @keyframes pulseWave {
      0% { r: 8px; opacity: 0.9; }
      100% { r: 42px; opacity: 0; }
    }
    .rad-wave1 { animation: pulseWave 2.7s cubic-bezier(0.2, 0.6, 0.35, 1) infinite; }
    .rad-wave2 { animation: pulseWave 2.7s 0.9s cubic-bezier(0.2, 0.6, 0.35, 1) infinite; }
    .rad-wave3 { animation: pulseWave 2.7s 1.8s cubic-bezier(0.2, 0.6, 0.35, 1) infinite; }

    /* Responsive Mobile layout */
    @media (max-width: 500px) {
      .grid {
        grid-template-columns: 1fr;
        gap: 10px;
      }
      .column-card {
        display: grid;
        grid-template-columns: 88px 1fr;
        grid-template-rows: auto 1fr;
        gap: 6px 12px;
        align-items: center;
        text-align: left;
        padding: 10px;
      }
      .title {
        grid-column: 1 / -1;
        margin-bottom: 2px;
        font-size: 14px;
      }
      .scene-box {
        grid-column: 1;
        grid-row: 2;
        height: 76px;
        margin-bottom: 0;
      }
      .scene-box svg {
        width: 80px;
        height: 56px;
      }
      .badge-group {
        grid-column: 2;
        grid-row: 2;
        gap: 4px;
      }
      .badge {
        font-size: 11px;
        padding: 3px 6px;
      }
    }
  </style>
</head>
<body>

  <div class="grid">
    
    <div class="column-card">
      <div class="title">Conduction</div>
      <div class="scene-box">
        <svg viewBox="0 0 120 80" width="100" height="68" aria-label="Conduction diagram showing vibrating bonded atoms">
          
          <line x1="25" y1="25" x2="60" y2="25" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />
          <line x1="60" y1="25" x2="95" y2="25" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />
          <line x1="25" y1="55" x2="60" y2="55" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />
          <line x1="60" y1="55" x2="95" y2="55" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />
          <line x1="25" y1="25" x2="25" y2="55" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />
          <line x1="60" y1="25" x2="60" y2="55" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />
          <line x1="95" y1="25" x2="95" y2="55" stroke="#94a3b8" stroke-width="2" stroke-dasharray="3,2" />

          
          <circle class="atom-hot" cx="25" cy="25" r="9" fill="#ea580c" />
          <circle class="atom-hot" cx="25" cy="55" r="9" fill="#ea580c" />
          <circle class="atom-mid" cx="60" cy="25" r="8" fill="#d97706" />
          <circle class="atom-mid" cx="60" cy="55" r="8" fill="#d97706" />
          <circle class="atom-cool" cx="95" cy="25" r="7" fill="#0284c7" />
          <circle class="atom-cool" cx="95" cy="55" r="7" fill="#0284c7" />
        </svg>
      </div>
      <div class="badge-group">
        <div class="badge-item">
          <span class="badge-label">Medium</span>
          <span class="badge badge-medium">Direct contact (solids)</span>
        </div>
        <div class="badge-item">
          <span class="badge-label">Bulk Flow</span>
          <span class="badge badge-flow-no">No bulk movement</span>
        </div>
      </div>
    </div>

    
    <div class="column-card">
      <div class="title">Convection</div>
      <div class="scene-box">
        <svg viewBox="0 0 120 80" width="100" height="68" aria-label="Convection diagram showing circular fluid loop">
          <defs>
            <linearGradient id="fluidGrad" x1="0%" y1="100%" x2="0%" y2="0%">
              <stop offset="0%" stop-color="#ea580c" />
              <stop offset="50%" stop-color="#d97706" />
              <stop offset="100%" stop-color="#0284c7" />
            </linearGradient>
          </defs>
          
          <rect x="25" y="15" width="70" height="50" rx="20" fill="none" stroke="url(#fluidGrad)" stroke-width="6" stroke-linecap="round" />
          <rect class="flow-path" x="25" y="15" width="70" height="50" rx="20" fill="none" stroke="#ffffff" stroke-width="2.5" stroke-linecap="round" />
          
          
          <polygon points="22,36 25,27 28,36" fill="#ea580c" />
          <polygon points="92,44 95,53 98,44" fill="#0284c7" />
        </svg>
      </div>
      <div class="badge-group">
        <div class="badge-item">
          <span class="badge-label">Medium</span>
          <span class="badge badge-medium">Fluids (liquids &amp; gases)</span>
        </div>
        <div class="badge-item">
          <span class="badge-label">Bulk Flow</span>
          <span class="badge badge-flow-yes">Yes (density flow)</span>
        </div>
      </div>
    </div>

    
    <div class="column-card">
      <div class="title">Radiation</div>
      <div class="scene-box">
        <svg viewBox="0 0 120 80" width="100" height="68" aria-label="Radiation diagram showing expanding electromagnetic waves">
          
          <circle class="rad-wave1" cx="60" cy="40" r="10" fill="none" stroke="#ea580c" stroke-width="2.5" />
          <circle class="rad-wave2" cx="60" cy="40" r="10" fill="none" stroke="#ea580c" stroke-width="2" />
          <circle class="rad-wave3" cx="60" cy="40" r="10" fill="none" stroke="#c2410c" stroke-width="1.5" />
          
          
          <circle cx="60" cy="40" r="8" fill="#ea580c" />
        </svg>
      </div>
      <div class="badge-group">
        <div class="badge-item">
          <span class="badge-label">Medium</span>
          <span class="badge badge-medium">None needed (vacuum)</span>
        </div>
        <div class="badge-item">
          <span class="badge-label">Bulk Flow</span>
          <span class="badge badge-flow-no">No (light-speed waves)</span>
        </div>
      </div>
    </div>
  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * { box-sizing: border-box; margin: 0; padding: 0; }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
      padding: 12px;
      user-select: none;
    }

    .header-bar {
      width: 100%;
      max-width: 600px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 13px;
      font-weight: 600;
      padding: 4px 8px;
    }

    .heat-label-left { color: #dc2626; display: flex; align-items: center; gap: 4px; }
    .heat-label-right { color: #2563eb; display: flex; align-items: center; gap: 4px; }

    .arrow-container {
      width: 100%;
      max-width: 600px;
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 20px;
      padding: 6px 14px;
      font-size: 13px;
      font-weight: 600;
      color: #475569;
      margin-bottom: 6px;
    }

    .arrow-flow {
      color: #ea580c;
      font-weight: 700;
      letter-spacing: 1px;
    }

    .canvas-container {
      position: relative;
      width: 100%;
      max-width: 600px;
      height: 240px;
      background: #f1f5f9;
      border-radius: 12px;
      overflow: hidden;
    }

    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }

    .controls {
      width: 100%;
      max-width: 600px;
      display: flex;
      gap: 8px;
      justify-content: center;
      margin-top: 10px;
      flex-wrap: wrap;
    }

    .btn {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #334155;
      padding: 7px 14px;
      border-radius: 8px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 5px;
      transition: background 0.2s, border-color 0.2s;
    }

    .btn.active {
      background: #2563eb;
      color: #ffffff;
      border-color: #2563eb;
    }
  </style>
</head>
<body>

  <div class="header-bar">
    <span class="heat-label-left">🔥 High Kinetic Energy</span>
    <span class="heat-label-right">Low Kinetic Energy ❄️</span>
  </div>

  <div class="arrow-container">
    <span>Heat Flow via Collisions</span>
    <span class="arrow-flow">➔ ➔ ➔</span>
  </div>

  <div class="canvas-container" id="canvasBox">
    <canvas id="simCanvas"></canvas>
  </div>

  <div class="controls">
    <button class="btn active" id="btnPlay" onclick="togglePlay()">⏸ Pause</button>
    <button class="btn" onclick="resetHeat()">↺ Reset</button>
  </div>

  <script>
    const canvas = document.getElementById('simCanvas');
    const ctx = canvas.getContext('2d');
    const box = document.getElementById('canvasBox');

    let width, height;
    function resize() {
      const rect = box.getBoundingClientRect();
      const dpr = window.devicePixelRatio || 1;
      width = rect.width;
      height = rect.height;
      canvas.width = width * dpr;
      canvas.height = height * dpr;
      ctx.scale(dpr, dpr);
    }
    window.addEventListener('resize', resize);
    resize();

    const COLS = 7;
    const ROWS = 3;
    let atoms = [];
    let isPlaying = true;
    let time = 0;

    function initAtoms() {
      atoms = [];
      for (let c = 0; c < COLS; c++) {
        for (let r = 0; r < ROWS; r++) {
          atoms.push({
            c, r,
            temp: c === 0 ? 1.0 : 0.05,
            vx: 0,
            vy: 0,
            offsetX: 0,
            offsetY: 0,
            phase: Math.random() * Math.PI * 2
          });
        }
      }
    }
    initAtoms();

    function resetHeat() {
      initAtoms();
    }

    function togglePlay() {
      isPlaying = !isPlaying;
      document.getElementById('btnPlay').innerHTML = isPlaying ? '⏸ Pause' : '▶ Play';
      document.getElementById('btnPlay').classList.toggle('active', isPlaying);
    }

    function getColor(temp) {
      // Interpolate from Cool Blue (#3b82f6) -> Yellow (#eab308) -> Hot Red/Orange (#ef4444)
      if (temp < 0.5) {
        const t = temp / 0.5;
        const r = Math.round(59 + t * (234 - 59));
        const g = Math.round(130 + t * (179 - 130));
        const b = Math.round(246 + t * (8 - 246));
        return `rgb(${r}, ${g}, ${b})`;
      } else {
        const t = (temp - 0.5) / 0.5;
        const r = Math.round(234 + t * (239 - 234));
        const g = Math.round(179 + t * (68 - 179));
        const b = Math.round(8 + t * (68 - 8));
        return `rgb(${r}, ${g}, ${b})`;
      }
    }

    function update() {
      if (isPlaying) {
        time += 0.04;

        // Conduction propagation along columns
        for (let i = 0; i < atoms.length; i++) {
          const a = atoms[i];
          if (a.c === 0) {
            a.temp = Math.min(1.0, a.temp + 0.005);
          } else {
            // Find neighbors in previous column
            let leftTempSum = 0;
            let leftCount = 0;
            atoms.forEach(neighbor => {
              if (neighbor.c === a.c - 1 && Math.abs(neighbor.r - a.r) <= 1) {
                leftTempSum += neighbor.temp;
                leftCount++;
              }
            });
            if (leftCount > 0) {
              const targetTemp = leftTempSum / leftCount;
              if (targetTemp > a.temp) {
                a.temp += (targetTemp - a.temp) * 0.006;
              }
            }
          }

          // Vibration amplitude scales directly with kinetic energy (temp)
          const amp = 1.5 + a.temp * 7.5;
          const speed = 4 + a.temp * 14;
          a.offsetX = Math.cos(time * speed + a.phase) * amp;
          a.offsetY = Math.sin(time * speed * 1.3 + a.phase) * amp;
        }
      }
    }

    function draw() {
      ctx.clearRect(0, 0, width, height);

      const rodMarginLeft = 65;
      const rodMarginRight = 30;
      const rodMarginTop = 35;
      const rodMarginBottom = 35;

      const rodWidth = width - rodMarginLeft - rodMarginRight;
      const rodHeight = height - rodMarginTop - rodMarginBottom;

      // Draw Metal Rod Outline & Solid Base
      ctx.fillStyle = '#e2e8f0';
      ctx.strokeStyle = '#94a3b8';
      ctx.lineWidth = 2;
      ctx.beginPath();
      ctx.roundRect(rodMarginLeft, rodMarginTop, rodWidth, rodHeight, 10);
      ctx.fill();
      ctx.stroke();

      const colSpacing = rodWidth / (COLS + 0.2);
      const rowSpacing = rodHeight / (ROWS + 0.2);

      // Draw Lattice Bonds
      ctx.strokeStyle = '#cbd5e1';
      ctx.lineWidth = 2;
      for (let i = 0; i < atoms.length; i++) {
        const a = atoms[i];
        const ax = rodMarginLeft + (a.c + 0.6) * colSpacing + a.offsetX;
        const ay = rodMarginTop + (a.r + 0.6) * rowSpacing + a.offsetY;

        for (let j = i + 1; j < atoms.length; j++) {
          const b = atoms[j];
          if ((Math.abs(a.c - b.c) === 1 && a.r === b.r) || (Math.abs(a.r - b.r) === 1 && a.c === b.c)) {
            const bx = rodMarginLeft + (b.c + 0.6) * colSpacing + b.offsetX;
            const by = rodMarginTop + (b.r + 0.6) * rowSpacing + b.offsetY;
            ctx.beginPath();
            ctx.moveTo(ax, ay);
            ctx.lineTo(bx, by);
            ctx.stroke();
          }
        }
      }

      // Draw Flame on the left
      const flameX = rodMarginLeft - 36;
      const flameY = rodMarginTop + rodHeight / 2;
      ctx.font = '32px sans-serif';
      ctx.textAlign = 'center';
      ctx.textBaseline = 'middle';
      ctx.fillText('🔥', flameX, flameY);

      // Draw Atoms
      for (let i = 0; i < atoms.length; i++) {
        const a = atoms[i];
        const ax = rodMarginLeft + (a.c + 0.6) * colSpacing + a.offsetX;
        const ay = rodMarginTop + (a.r + 0.6) * rowSpacing + a.offsetY;
        const radius = 10 + a.temp * 2.5;

        // Outer glow for hot atoms
        if (a.temp > 0.3) {
          ctx.beginPath();
          ctx.arc(ax, ay, radius + a.temp * 6, 0, Math.PI * 2);
          ctx.fillStyle = `rgba(239, 68, 68, ${a.temp * 0.25})`;
          ctx.fill();
        }

        // Atom sphere
        ctx.beginPath();
        ctx.arc(ax, ay, radius, 0, Math.PI * 2);
        ctx.fillStyle = getColor(a.temp);
        ctx.fill();
        ctx.strokeStyle = '#ffffff';
        ctx.lineWidth = 1.5;
        ctx.stroke();

        // Specular highlight
        ctx.beginPath();
        ctx.arc(ax - radius * 0.3, ay - radius * 0.3, radius * 0.25, 0, Math.PI * 2);
        ctx.fillStyle = 'rgba(255, 255, 255, 0.6)';
        ctx.fill();
      }
    }

    function loop() {
      update();
      draw();
      requestAnimationFrame(loop);
    }
    loop();
  </script>
</body>
</html>

OGS.9.PS.7

Aligned learning resources

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