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[
{
"slide": 1,
"fragments": [
{
"fragment_index": 1,
"text_description": "Why Won’t It Budge?\nStarting to push a heavy cupboard is harder than keeping it moving.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "First shove must beat static friction; after that sliding is easier.",
"image_description": "https://asset.sparkl.ac/pb/sparkl-vector-images/img_ncert/PHkJpNmR6gI236OSJaoIOqiwyvAb6FtwLeyAzMrj.png"
},
{
"fragment_index": 3,
"text_description": "Scenario\nYou push a heavy cupboard resting on the floor.",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "What happens\nStatic friction opposes your force up to its maximum value.\nYou must exceed this maximum to set the cupboard in motion.\nOnce moving, smaller kinetic friction keeps resisting, so less push is needed.",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "Takeaway: Static friction is usually larger than kinetic friction—hence the tough first shove.",
"image_description": ""
}
]
},
{
"slide": 2,
"fragments": [
{
"fragment_index": -1,
"text_description": "Multiple Choice Question\nCorrect!\nYes—static friction holds objects at rest.\nIncorrect\nNot quite. Think before sliding starts.\nconst correctOption = 0;\n const answerCards = document.querySelectorAll('.answer-card');\n const submitBtn = document.getElementById('slide-02-a1b2c3-submit');\n const feedbackCorrect = document.getElementById('slide-02-a1b2c3-feedback-correct');\n const feedbackIncorrect = document.getElementById('slide-02-a1b2c3-feedback-incorrect');\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\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 });",
"image_description": ""
},
{
"fragment_index": 1,
"text_description": "Question\nThe sofa resists motion chiefly because of _____ between its legs and the floor.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "1\nstatic friction",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\nkinetic friction",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\nair drag",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "4\nnormal force",
"image_description": ""
},
{
"fragment_index": 6,
"text_description": "Hint:\nIt acts before motion begins.",
"image_description": ""
},
{
"fragment_index": 7,
"text_description": "Submit Answer",
"image_description": ""
}
]
},
{
"slide": 3,
"fragments": [
{
"fragment_index": 1,
"text_description": "What Causes Friction?\nMicroscopic view: rough peaks, interlocking, and adhesion.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "1\nMicroscopic roughness\nEven polished surfaces have tiny bumps called\nasperities\n.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\nInterlocking bumps\nAsperities fit together and resist relative motion until enough force breaks the locks.",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\nAdhesive forces\nAtoms at the contact points share electrons, creating\nadhesion\nthat adds to friction.",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "Heavier loads press asperities closer, strengthening both interlocking and adhesion.",
"image_description": ""
}
]
},
{
"slide": 4,
"fragments": [
{
"fragment_index": 1,
"text_description": "Static vs Kinetic Friction\nUse relative motion to tell them apart.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "Static friction\nNo relative motion between surfaces.\nAdapts up to a limit: \\(F_s \\le \\mu_s N\\).\nOpposes impending motion.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "Kinetic friction\nSurfaces slide in relative motion.\nNearly constant: \\(F_k = \\mu_k N\\).\nOpposes actual motion.",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "Common ground\nBoth act parallel to the contact surface.\nMagnitude depends on normal force \\(N\\) and surface pair.\nDisappear if contact is removed.",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "Usually \\( \\mu_s > \\mu_k \\). Decide relative motion first, then choose the correct formula.",
"image_description": ""
}
]
},
{
"slide": 5,
"fragments": [
{
"fragment_index": -1,
"text_description": "Maximum Static Friction\nMaximum static friction equals the coefficient of static friction multiplied by the normal reaction \\(N\\), which acts perpendicular to the surface.\nSource: NCERT Eq. 4.13",
"image_description": ""
},
{
"fragment_index": 1,
"text_description": "\\( f_s^{\\text{max}} = \\mu_s N \\)",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "Here, \\( \\mu_s \\) is unit-less and typically lies between 0 and 1.",
"image_description": ""
}
]
},
{
"slide": 6,
"fragments": [
{
"fragment_index": -1,
"text_description": "Kinetic Friction Law\nSource: NCERT Eq. 4.14",
"image_description": ""
},
{
"fragment_index": 1,
"text_description": "\\(f_k = \\mu_k N\\)",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "Kinetic friction opposes sliding motion. Its magnitude equals the product of the coefficient of kinetic friction and the normal reaction.\n\\(\\mu_k\\) stays nearly constant for a given surface pair at moderate speeds—use the relation to find friction on any steadily moving object.",
"image_description": ""
}
]
},
{
"slide": 7,
"fragments": [
{
"fragment_index": 1,
"text_description": "Block on an Incline\nResolve forces and spot the friction direction.",
"image_description": ""
},
{
"fragment_index": -1,
"text_description": "N\nmg\n\\(mg\\sin\\theta\\)\n\\(mg\\cos\\theta\\)\n\\(f_s\\)\nGravity splits into \\(mg\\sin\\theta\\) along and \\(mg\\cos\\theta\\) perpendicular; static friction opposes the slide.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "Will it slide down?\nThe downhill pull \\(mg\\sin\\theta\\) must beat the maximum static friction to start motion.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "Parallel pull: \\(mg\\sin\\theta\\) down the plane.\nNormal force: \\(N = mg\\cos\\theta\\) perpendicular.\nStatic friction \\(f_s\\) points up the plane, opposing possible slide.",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "Tip: Motion begins when \\(mg\\sin\\theta = \\mu_s N\\). Increase θ to reach the “angle of repose.”",
"image_description": ""
}
]
},
{
"slide": 8,
"fragments": [
{
"fragment_index": 1,
"text_description": "Worked Example\n2 kg block on \\(30^{\\circ}\\) incline, \\(\\mu_k = 0.2\\). Find its acceleration.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "1\nDraw forces\nShow \\(mg\\sin\\theta\\) down-slope, \\(N\\) normal, \\(f_k\\) up-slope.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\nNormal force\n\\(N = mg\\cos\\theta = 2 \\times 9.8 \\times \\cos30^{\\circ} \\approx 17 \\text{ N}\\).",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\nCalculate \\(f_k\\)\n\\(f_k = \\mu_k N = 0.2 \\times 17 \\approx 3.4 \\text{ N}\\).",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "4\nNet force\n\\(F_{\\text{net}} = mg\\sin\\theta - f_k \\approx 9.8 - 3.4 = 6.4 \\text{ N}\\).",
"image_description": ""
},
{
"fragment_index": 6,
"text_description": "5\nAcceleration\n\\(a = \\frac{F_{\\text{net}}}{m} = \\frac{6.4}{2} = 3.2 \\text{ m/s}^2\\).",
"image_description": ""
},
{
"fragment_index": 7,
"text_description": "Use \\(\\mu_k\\) because the block is moving; \\(\\mu_s\\) applies only before motion starts.",
"image_description": ""
}
]
},
{
"slide": 9,
"fragments": [
{
"fragment_index": -1,
"text_description": "Multiple Choice Question\nSubmit Answer\nCorrect!\nWell done.\nIncorrect\nRe-calculate \\(\\mu_s N\\).\nconst correctOption = 1; // index of 49 N\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\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 });",
"image_description": ""
},
{
"fragment_index": 1,
"text_description": "Question\nA 10 kg crate rests on a level floor where the coefficient of static friction is 0.5. \n What horizontal force just starts it moving? Choose the closest value of \n \\(f_s^{\\text{(max)}}\\).",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "1\n25 N",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\n49 N",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\n50 N",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "4\n98 N",
"image_description": ""
},
{
"fragment_index": 6,
"text_description": "Hint:\nNormal force \\(N = mg\\) on level ground.",
"image_description": ""
}
]
},
{
"slide": 10,
"fragments": [
{
"fragment_index": 1,
"text_description": "Common Pitfall: Direction of Friction",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "Friction opposes\nrelative\nmotion of the two surfaces.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "It is not always opposite to the object’s velocity.",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "Pull a rug under a vase: friction drags the vase forward with the rug.",
"image_description": ""
}
]
},
{
"slide": 11,
"fragments": []
},
{
"slide": 12,
"fragments": [
{
"fragment_index": 1,
"text_description": "Key Takeaways — Friction\nKnow these four points to recall the concept.",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "1\nStatic > Kinetic\nStarting friction is higher than sliding for most dry surfaces.",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\nLinear law\n\\(f_s^{\\text{max}}=\\mu_s N\\), \\(f_k=\\mu_k N\\).",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\nOpposes motion\nActs opposite to relative motion or its tendency.",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "4\nMaterial dependent\nCoefficients \\(\\mu\\) vary with the surface pair.",
"image_description": ""
}
]
},
{
"slide": 13,
"fragments": [
{
"fragment_index": -1,
"text_description": "Multiple Choice Question\nSubmit Answer\nCorrect!\nExactly! The backward push of the tyre produces an equal forward friction force.\nIncorrect\nRemember Newton’s third law at the tyre–road contact.\nconst correctOption = 0;\n const answerCards = document.querySelectorAll('.answer-card');\n const submitBtn = document.getElementById('slide-13-a1b2c3-submit');\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 \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 });",
"image_description": ""
},
{
"fragment_index": 1,
"text_description": "Question\nOn a level road, the car experiences forward friction during acceleration because:",
"image_description": ""
},
{
"fragment_index": 2,
"text_description": "1\nTyres push the road backward",
"image_description": ""
},
{
"fragment_index": 3,
"text_description": "2\nVehicle weight increases",
"image_description": ""
},
{
"fragment_index": 4,
"text_description": "3\nAir pushes the car forward",
"image_description": ""
},
{
"fragment_index": 5,
"text_description": "4\nThe normal force tilts forward",
"image_description": ""
},
{
"fragment_index": 6,
"text_description": "Hint:\nThink action–reaction between tyre and road.",
"image_description": ""
}
]
}
]