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SI unit
- The International System of Units (abbreviated SI from the French language name Système International d’Unités) is the modern form of the metric system.
- It is the world’s most widely used system of units, both in everyday commerce and in science.
Derived Unit
- The derived unit is a combination of base units through multiplying and/or dividing them.
- For instance, Speed is defined as the rate of distance change, and can be written in the mathematic form
Example:
Find the derived unit of density.
Answer:
Conversion of the Unit of Speed, Density and Pressure
- When doing the conversion of unit such as speed and density, we are advised to write the quantity in the fraction form.
- For example, to convert 5km/h to m/s, we write 5km/h as
- After that, we convert the km to m and h (hour) to s (second)
Example
Complete the following unit conversion of speed.
- 90 kmh-1 = __________ ms-1
- 8.12 ms-1 = __________ kmh-1
Answer:
Example
Complete the following unit conversion of density and pressure.
- 760 kgm-3 = __________ gcm-3
- 5.1 gcm-3 = __________ kgm-3
- 3600 Nm-2 = __________ Ncm-2
- 3.16×10-5 Ncm-2= __________ Nm-2
Answer:
a.
b.
c.
d.