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Measurement. Self Study Package for 3B1. Contents. 1. What is a quantity? 2. Base quantities & Derived quantities 3. Standard Form 4. Prefixes. What is a Physical Quantity?. A Physical Quantity is a quantity that can be measured . Quantity – number
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Measurement Self Study Package for 3B1
Contents • 1. What is a quantity? • 2. Base quantities & Derived quantities • 3. Standard Form • 4. Prefixes
What is a Physical Quantity? • A Physical Quantity is a quantity that can be measured. • Quantity – number • Measured – describing something in the real physical world
What is a Physical Quantity? • Most physical quantities have a numerical magnitude and a unit Numerical Magnitude Unit 10 cm
7 Base Quantities • You are required to memorize the 7 base quantities and their units
Derived Quantities • However, there are more than 7 physical quantities in real life. What about the rest? • The rest are called derived quantities • They can be derived using from the 7 base quantities, provided you know the relevant formula • E.g. Speed = Length / Time • Length & Time are base quantities • Speed is a derived quantity
Derived Quantities • Test yourself – Express density into its base quantities. • Density = Mass / Volume • Since Volume = Length x Length x Length • Density = Mass / (Length x Length x Length) • Or = Mass / (Length)3
Derived Units • If Physical Units can be broken down into it’s base quantities • Units can also be broken down into it’s base units. E.g. Units of speed = unit of length / unit of time • = m/s • = ms-1 (For Physics, please express units in this “indices” form)
Standard Form • You have already learned standard form from Mathematics. • It is a form which prevents us from writing very long numbers for very big or very small quantities. • E.g. the speed of light is • 299792458 ms-1 [not in standard form] • 3.00 x 108ms-1 [in standard form] • Please note: If your answer to any Physics question is more than 4 digits long, convert it to standard form, 3 sig. fig.
Prefixes (Pg 4) • You are required to memorize the following prefixes: • Important: uppercase or lowercase!
To Be Continued… • These slides cover the topics which would be covered in the Common Test. • We will cover the other subtopics after your common test. • Work hard and best of luck for your common test!