Class 7 Science — Chapter 8: Measurement of Time and Motion

What you'll learn

• ▸Ancient Timekeeping Devices
• ▸The Simple Pendulum and Oscillatory Motion
• ▸Oscillation and Time Period
• ▸Galileo's Contribution to Timekeeping
• ▸Measuring the Time Period of a Pendulum
• ▸Factors Affecting the Time Period
• ▸SI Unit of Time
• ▸Principle of Modern Clocks

Chapter Summary

--- PAGE 1 --- 8 Measurement of Time and Motion Prerna and her younger sister are watching a sports channel on television. Prerna enjoys running and she has been declared the fastest runner among the girls in her district for winning the 100 metre sprint at an interschool competition held at the district level. She is now training to compete at the state level. She dreams of representing India at the international level in 100 metre sprint contests in future. 0777CH08 While watching the rerun of sprints at the Olympic games held in the past, Prerna is always amazed that the measurement of the time taken for the race is so advanced that they could identify the winner even when two sprinters seemed to cross the finish line almost together. However, in her school, the sports teacher only used a special kind of watch called a ‘stopwatch’ for timing the school races. She had noticed her mother wearing a watch on her wrist and her sister looking at her mobile phone when she needed to chec…

Practice Questions from this Chapter

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1. Build a simple sundial? Get Solution →
2. Describe pendulum motion? Get Solution →
3. Explain atomic clocks? Get Solution →
4. What is the SI unit of time? Get Solution →
5. Which ancient device measures time based on the flow of sand from one bulb to another? Get Solution →
6. What is the small metallic ball suspended in a simple pendulum called? Get Solution →
7. Who is credited with inventing the pendulum clock in 1656? Get Solution →
8. In a sundial, time is determined by the changing position of what? Get Solution →

Did you know?

• 💡 Ancient Egyptians used tall stone obelisks as massive sundials.
• 💡 Atomic clocks measure time by the vibrations of atoms, not mechanical parts.
• 💡 The Earth's rotation is slowing down, making our days slightly longer.
• 💡 A Foucault's Pendulum proves the Earth is constantly spinning.
• 💡 Before mechanical clocks, people often told time by watching shadows or burning candles.

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