3NA Science (Physics) Chapter 1 Physical Quantities, Units and Measurement
By the end of the lesson, you should be able to
Physical Quantities <ul><li>A physical property is a quantity that can be measured </li></ul><ul><li>Can you name some physical quantities? </li></ul>
Imagine you ask about the age of a person, and the number is a numerical value. The information conveyed during the conversation will not be very specific or useful. How old is your little sister, Jon? She is 12! 12? 12 months? 12 years old?
No NAKED numbers please!!! <ul><li>Do these numbers make sense to you? </li></ul><ul><li>What do they lack? </li></ul><ul><li>45 897.00 </li></ul><ul><li>67000 </li></ul><ul><li>0.325 3 x 10 8 </li></ul>
Quantities, Magnitude, Units <ul><li>The weight of a coin is 12 g . </li></ul>Physical quantity magnitude unit All physical quantities are presented with a magnitude and a unit .
Base Quantities and its Unit m metre length mol mole Amount of substance A ampere current s second time cd candela Luminous intensity K kelvin temperature kg kilogram mass Symbol Base unit Base quantity
Very small and very BIG quantities A more efficient way of expressing very big or very small number is to do so in scientific notation, using appropriate prefixes . Bacteria is very small…..it is about 0.000 001 m long… The sun is 149 342 000 000 m away from us…
Prefixes giga (G) mega (M) kilo (k) deci (d) centi (c) milli (m) micro ( ) nano (n) X 10 9 X 10 6 X 10 3 X 10 -1 X 10 -2 X 10 -3 X 10 -6 X 10 -9 X 1 000 000 000 X 1 000 000 X 1 000 X 0.1 X 0.01 X 0.001 X 0.000 001 X 0.000 000 001