Class 7 Science Chapter 8 Measurement of Time and Motion Notes | Curiosity 2026-27 | Amresh Academy

 

 

🌟 Class 7 Science Curiosity – Chapter 8 Notes

⏱️ Measurement of Time and Motion | Amresh Academy

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📘 Introduction

Time and motion are important in our daily life ⏳

👉 We measure time to understand events and movement (motion)

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🕰️ 1. Measurement of Time

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🏺 Ancient Timekeeping Devices

• 🌞 Sundial → Uses shadow of sunlight
• 💧 Water Clock → Measures time by water flow
• ⏳ Hourglass → Uses sand flow
• 🕯️ Candle Clock → Based on burning rate

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🌟 Interesting Fact:

👉 Ghatika-yantra measured time in ghati (24 minutes)

👉 1 day = 60 ghatis

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⚙️ Evolution of Clocks

• ⏱️ Mechanical Clocks (14th century) → gears & springs
• 🕰️ Pendulum Clocks (17th century) → by Christiaan Huygens
• ⌚ Modern Clocks → Quartz & Atomic clocks

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🔄 2. Simple Pendulum

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📌 Definition:

👉 A small metal ball (bob) tied to a string

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🔁 Oscillation:

👉 One complete to-and-fro motion

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⏳ Time Period:

👉 Time taken for one oscillation

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🧠 Key Points:

• Depends on length of pendulum
• Does NOT depend on mass

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🧪 Activity:

👉 Time for 10 oscillations ÷ 10 = Time period

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📏 3. SI Unit of Time

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👉 Second (s) is SI unit

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📊 Conversions:

• 60 seconds = 1 minute
• 60 minutes = 1 hour

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📌 Rules:

• Use lowercase (s, min, h)
• Leave space (e.g., 5 s)
• No full stop

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🚀 4. Speed

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📌 Definition:

👉 Distance covered in unit time

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📐 Formula:

[

\text{Speed} = \frac{\text{Distance}}{\text{Time}}

]

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📊 Units:

• SI unit → m/s
• Common → km/h

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🔄 Other Formulas:

• Distance = Speed × Time
• Time = Distance ÷ Speed

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⚡ Average Speed:

👉 Total distance ÷ Total time

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🚆 5. Uniform and Non-Uniform Motion

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📌 Linear Motion:

👉 Motion in a straight line

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✔️ Uniform Motion:

• Same speed
• Equal distances in equal time

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❌ Non-Uniform Motion:

• Speed changes
• Unequal distances

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🚗 Examples:

• Train at constant speed → Uniform
• Car in traffic → Non-uniform

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📌 Final Summary

👉 Time helps us measure events ⏳

👉 Motion helps us understand movement 🚀

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🔑 Key Concepts:

• Ancient to modern clocks 🕰️
• Pendulum motion 🔄
• Speed calculation 📐
• Types of motion 🚗

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✨ Perfect for revision + exams + concept clarity 🚀

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