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[accordion title="1. Base and Derived Quantities"]

- Physical quantities are classified as base (or fundamental) quantities and derived quantities.

7**base quantities**are chosen to form the base units.

Base Quantity |
Base Unit |

mass | kilogram (kg) |

length | metre (m) |

time | second (s) |

electric current | ampere (A) |

temperature | kelvin (K) |

amount of substance | mole (mol) |

luminous intensity | candela (cd) |

- Any other physical quantities can be derived from these base quantities. These are called
**derived quantities**.

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[accordion title="2. Prefixes"]

- Prefixes are attached to a unit when dealing with very large or very small numbers.

Power |
Prefix |

pico (p) | |

nano (n) | |

micro () | |

milli (m) | |

centi (c) | |

deci (d) | |

kilo (k) | |

mega (M) | |

giga (G) | |

tera (T) |

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[accordion title="3. Homogeneity of A Physical Equation"]

- A physical equation is said to be homogeneous if each of the terms, separated by plus, minus, equality or inequality signs has the same base units.

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[accordion title="4. Uncertainty"]

**Absolute uncertainty**of a measurement of can be written as . This means that true value of the measurement is likely to lie in the range to .**Fractional uncertainty**=**Percentage uncertainty**=- If the values of two or more quantities such as and are measured and then these are combined to determine another quantity , the absolute or percentage uncertainty of can be calculated as follows:
- If , then
- If or , then
- If then

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[accordion title="5. Errors"]

**Systematic errors**are errors that, upon repeating the measurement under the same conditions, yield readings with error of same magnitude and sign.**Random errors**are errors that, upon repeating the measurement under the same conditions, yield readings with error of different magnitude and sign.

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[accordion title="6. Accuracy and Precision"]

- The
**accuracy**of an experiment is a measure of how close a measured value is to the true value. It is a measure of the correctness of the result. - The
**precision**of an experiment is a measure of how exact the result is without reference to what that the result means. It is a measure of how reproducible the results are, i.e. it is a measure of how small the uncertainty is.

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[accordion title="7. Vectors"]

- A
**vector**quantity has magnitude and direction. - A
**scalar**quantity has magnitude only. - Addition of vectors in 2D:

- Methods of finding magnitudes of vectors:
- resolution of vectors into perpendicular components
- by scale drawing
- using:

**sine rule**:

**cosine rule**:

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