# Physical Quantities and Units

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What is Quantity?
It is the amount of something e.g. number of cards in a deck; 52
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What is unit?
A standard measure of a quantity e.g. Metres for distance
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Quantity example Pt 1.
Scalar (depended on magnitude) e.g. mass of an object
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Quantity example Pt 2.
Vector (depended on direction) e.g. velocity or acceleration
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What is SI unit? (Base/Fundamental)
A complete metric system of units of measurement, internationally agreed upon and universally used.
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What are the 6 SI unit? (only 6 for A-level)
Time (s); Length (m); Mass (kg); Current (A); Temperature (K) & Amount of substance (mol)
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What is Derived Quantity (Unit)?
Derived quantities are physical quantities derived from combinations of base quantities through multiplications
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Give an example of a derived unit
F (force) = m (Mass) × a (acceleration) ---> N = kg ms^-2
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What is prefix?
A prefix is a symbol that you place in front of a unit e.g mm--> m (milli) m (metre)
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Why is prefix used in physics?
A measurement can be unusually too small or large which makes it difficult to work with, hence prefix is used
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Give an example of prefix in physics
Name: Giga Symbol: G Multiple of: 10^9
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## Other cards in this set

### Card 2

What is unit?

#### Back

A standard measure of a quantity e.g. Metres for distance

### Card 3

#### Front

Quantity example Pt 1.

### Card 4

#### Front

Quantity example Pt 2.

### Card 5

#### Front

What is SI unit? (Base/Fundamental)