Concept 3 of 8Foundation
Watch on YouTubeVideoNeed for standard measurement
Long ago, people used body parts: handspan, cubit (elbow-to-fingertip), foot. Problem? Your hand and mine are different!
A standard unit gives the same answer everywhere — same for you, me, a farmer in Egypt, an astronaut in space.
Modern scientists use SI (International System):
- Length → metre (m)
- Mass → kilogram (kg)
- Time → second (s)
- Temperature → kelvin (K)
Example
Someone says "the room is 12 feet." Whose foot? A small child's? SI says: "3.6 metres." No confusion.
💡 Tip:Always write the UNIT with a number. '50' is meaningless. '50 cm' has meaning.
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5 questions to check what you just read.
0 / 5
- Q1.SI unit of length:
- Q2.SI unit of mass:
- Q3.SI unit of time:
- Q4.A non-standard unit example:
- Q5.Why do we use standard units?