Measuring Time

The history of clocks from sundials to atomic clocks, and how pendulums work. Class 7 Science with quiz.

Class 7 ScienceClass 7 / Grade 7Ages 9–12
Lesson
⏱️ Measuring Time
Humans have measured time for 5,000 years!☀️Sun dialancient shadowclockSandglasstimed intervalsmanually🕰️PendulumGalileo'sdiscoveryQuartz watchvibratingcrystal⚛️Atomic clockaccurate to1 second/300yrAll clocks work by counting a regular repeating event!

Humans have been measuring time for at least five thousand years. All clocks work by the same principle: counting a regular repeating event. Sundials counted the shadow of the sun. Sandglasses counted falling sand grains. A pendulum clock counts the swing of a pendulum. A quartz watch counts the vibrations of a quartz crystal — thirty-two thousand seven hundred and sixty-eight times per second. Atomic clocks count atomic vibrations and are accurate to within one second over three hundred years.

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