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[
{
"slide": 1,
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"text_description": "Friction Basics\nWhere motion meets resistance—and sparks understanding.",
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"slide": 2,
"fragments": [
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"fragment_index": 1,
"text_description": "What is Friction?",
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"fragment_index": 2,
"text_description": "Friction",
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"text_description": "Friction is a contact force that acts parallel to the common surface and always opposes impending or actual relative motion between the surfaces.\nPause & think: Could you walk if friction suddenly vanished?",
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}
]
},
{
"slide": 3,
"fragments": [
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"fragment_index": -1,
"text_description": "Static vs Kinetic",
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"text_description": "",
"image_description": "https://asset.sparkl.ac/pb/sparkl-vector-images/img_ncert/PHkJpNmR6gI236OSJaoIOqiwyvAb6FtwLeyAzMrj.png"
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"text_description": "Spot the difference\nStatic friction \\(f_s\\) rises from zero up to its maximum value \\((f_s)_{\\text{max}}=\\mu_s N\\) to keep the body at rest.\nAfter motion starts, kinetic friction \\(f_k=\\mu_k N\\) acts; it stays nearly constant and is smaller than \\((f_s)_{\\text{max}}\\).\nKey Points:\n\\((f_s)_{\\text{max}} > f_k\\); extra push needed to start motion.\nBoth forces act parallel to surfaces, opposite to motion or its tendency.\nMagnitudes depend on surface pair via coefficients \\(\\mu_s\\) and \\(\\mu_k\\).",
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{
"slide": 4,
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"text_description": "μ — The Friction Factor",
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"text_description": "Coefficient of Friction (μ)\nDimensionless ratio of limiting friction to the normal reaction between two surfaces.\nKey Characteristics:\nStatic: \\( \\mu_s = \\frac{f_s^{\\text{max}}}{N} \\)\nKinetic: \\( \\mu_k = \\frac{f_k}{N} \\)\nDepends only on material pair and surface condition.\nUsually \\( \\mu_s > \\mu_k \\).\nIndependent of mass and apparent contact area.\nExample:\nDry wood on wood: \\( \\mu_s \\approx 0.4 \\), \\( \\mu_k \\approx 0.3 \\).",
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{
"slide": 5,
"fragments": [
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"fragment_index": -1,
"text_description": "Friction on an Incline\nForces on the Block",
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{
"fragment_index": 1,
"text_description": "Block on inclined plane showing weight components and friction",
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{
"fragment_index": 2,
"text_description": "A block of mass \\(m\\) rests on a rough incline at angle \\(\\theta\\).",
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{
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"text_description": "Its weight splits into \\(mg\\cos\\theta\\) (normal) and \\(mg\\sin\\theta\\) (down-slope).",
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{
"fragment_index": 4,
"text_description": "Key Points:\nStatic friction \\(f_s\\) acts up the plane, balancing \\(mg\\sin\\theta\\) while \\(f_s \\le \\mu_s N\\).\nLimiting case: \\(f_s^{\\text{max}} = \\mu_s N = mg\\sin\\theta_r\\) with \\(N = mg\\cos\\theta_r\\).\nAngle of repose: \\(\\theta_r = \\tan^{-1}\\mu_s\\); beyond it the block begins to slide.",
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},
{
"slide": 6,
"fragments": [
{
"fragment_index": 1,
"text_description": "Force vs Friction Curve",
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"text_description": "",
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"fragment_index": 3,
"text_description": "Static–Kinetic Transition",
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{
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"text_description": "In the static region, friction \\(f_s\\) equals the applied force, giving a straight 45° line.",
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{
"fragment_index": 5,
"text_description": "At \\((f_s)_{\\text{max}}\\) the object slips; friction drops to the lower, nearly constant kinetic value \\(f_k\\).",
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{
"fragment_index": 6,
"text_description": "Key Points:\n\\(f_s\\) rises linearly with applied force.\nPeak \\((f_s)_{\\text{max}}\\) marks the breakaway point.\nPost-slip friction ≈ constant kinetic value \\(f_k\\).",
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},
{
"slide": 7,
"fragments": []
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{
"slide": 8,
"fragments": [
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"fragment_index": -1,
"text_description": "Multiple Choice Question\nSubmit Answer\nCorrect!\nStatic friction balances the 12 N push while the box remains still, so its value is 12 N opposite the applied force.\nIncorrect\nBecause the box is not moving, kinetic friction cannot act. Static friction must equal the 12 N push to keep it at rest.\nconst correctOption = 0;\n const answerCards = document.querySelectorAll('.answer-card');\n const submitBtn = document.getElementById('submitBtn');\n const feedbackCorrect = document.getElementById('feedbackCorrect');\n const feedbackIncorrect = document.getElementById('feedbackIncorrect');\n \n let selectedOption = null;\n \n answerCards.forEach((card, index) => {\n card.addEventListener('click', () => {\n answerCards.forEach(c => c.classList.remove('border-blue-500', 'bg-blue-50'));\n card.classList.add('border-blue-500', 'bg-blue-50');\n selectedOption = index;\n });\n });\n \n submitBtn.addEventListener('click', () => {\n if (selectedOption === null) return;\n if (selectedOption === correctOption) {\n feedbackCorrect.classList.remove('hidden');\n feedbackIncorrect.classList.add('hidden');\n } else {\n feedbackIncorrect.classList.remove('hidden');\n feedbackCorrect.classList.add('hidden');\n }\n });",
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{
"fragment_index": 1,
"text_description": "Question\nA 5 kg box stays at rest when a 12 N horizontal force pushes it. Which statement is\ntrue\n?",
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{
"fragment_index": 2,
"text_description": "1\nStatic friction on the box is 12 N opposite to the push.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\nKinetic friction on the box is 12 N opposite to the push.",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\nNo friction acts because the box does not slide.",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "4\nThe box moves because 12 N exceeds maximum static friction.",
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},
{
"fragment_index": 6,
"text_description": "Hint:\nSince the box is at rest, think about\nstatic\nfriction matching the applied force up to its limit.",
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}
]
},
{
"slide": 9,
"fragments": [
{
"fragment_index": -1,
"text_description": "Key Takeaways",
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{
"fragment_index": 1,
"text_description": "Definition\nFriction is a parallel contact force opposing imminent or actual sliding.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "Coefficient \\( \\mu \\)\nMagnitude \\(F = \\mu N\\); μ reflects material pair, surface finish, temperature, and contaminants.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "Static vs Kinetic\nStatic friction rises to \\( (\\!f_s)_{\\max} = \\mu_s N\\); once moving, \\(f_k = \\mu_k N\\) stays lower.",
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},
{
"fragment_index": 4,
"text_description": "Graph Shape\nCurve climbs linearly, peaks, then drops abruptly to a nearly constant kinetic level.",
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},
{
"fragment_index": 5,
"text_description": "Applications\nLubricants, bearings, brakes, and tyre treads let engineers reduce or exploit friction as needed.",
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}
]
}
]