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• February 16, 2022

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• PHY101 Physics I © Dr.Cem Özdoğan

• 1-5 Lengths

• Unit of length: “Meter” was originally defined in terms of the distance measured along the earth’s surface between North pole (point A) and Equator  (Point B).
• 1 meter ≡  AB/10 000000
• Eventually, a more accurate standard was needed, and by international agreement the meter became the distance between two marks on a bar of platinum-iridium alloy kept at 0 °C.
• Today meter is defined as the distance traveled by light in vacuum during a time interval of 1/299 792 458 of a second.
• This definition arises because the speed of light is a universal constant and is defined to be 299 792 458 m/s.