A.1 · 2 · Opening of A.1 Kinematics · link to periodic motion (Theme C)
Repeating motion and the birth of clocks
How repetition gave us a way to measure time.
SL+HLMedium14 minFree
Hook
Before watches and phones, how did anyone know how long a day, a month or a year was?
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Which is a man-made periodic motion?
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A pendulum takes 2.0 s per complete swing. Its frequency is…
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Why did people move from natural to man-made periodic motion?
Apply
Explain why a pendulum is a better timekeeper than the moon’s phases.
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Remember earlier lessons
From lesson A.1 · 1
Motion means…
From lesson 0.3
The SI base unit of time is…
Summary card
Key points
- • Repeating motion is periodic.
- • Natural periodic motion first measured time, but not precisely.
- • Pendulums and quartz are precise.
Formulas
- f = 1/T
- T = 2π√(L/g)
Key terms
- Period T :
- time for one repeat
- Frequency f :
- repeats per second
Common errors
- • Mixing up period and frequency.
- • Using big swings with the simple formula.
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