Units and Standards
1. Units and Standards
There are 4 fundamental scientific measurements: Mass, Length, Time, and Electric Charge
The following table summarizes their basic SI (International Metric System) units
Fundamental Quantity | Mass |
Length, distance, displacement |
Time | Charge |
SI Unit | kg (kilogram) | m (metre) | s (second) | C (coulomb) |
Symbol | m | Δd | t | Q |
2. Scalar vs. Vector
Scalar quantities express only a quantity and a unit
Vector quantities express a quantity, a unit and a direction
Examples:
Quantity | Symbol | Type | Example |
distance | Δd | scalar | Δd = 10 m |
displacement |
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vector |
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Note the arrow on the symbol for a vector
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It symbolizes the direction property of the vectory.