iGCSE GENERAL PHYSICS NOTES

Physics IGCSE Class May/June 2021
“General Physics”




Ahmed Shawky El-Gendy
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Ahmed Shawky El-Gendy
Cellular#: +201011557162

, Physics IGCSE Class May/June 2021
“General Physics”




* Measurements in Physics




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 Have you ever been to a market and seen how the fruit sellers
weighing the fruits?
 Have you ever watched a builder measuring the length of iron or
wood?
 What measuring instruments do they use? Do you know the
function of measurements??!!
 Measurement is very important in our daily life. There are many kind
of measuring instruments such as
 Ruler for measuring length
 Balance for measuring mass
 Stop watch for measuring time
 Thermometer for measuring temperature ……………etc




 Physical quantities:
Physical quantities are something that can be measured and expressed
with certain value of number (quantified) and having a related unit

No. Physical quantity Values Units
1 Length 2 Meters
2 Mass 5 Kilograms
3 Time 30 Seconds


 Kindness, love, and beauty do not belong to physical quantities
because they are abstract, and thus we can’t measure and quantify
them.

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Ahmed Shawky El-Gendy
Cellular#: +201011557162

, Physics IGCSE Class May/June 2021
“General Physics”
 Measurement:
Measurement is defined as a process of comparing a quantity with
other similar quantity that has already defined as a unit of
measurement.
“Unit of measurement is a standardized quantity of a physical property”




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 Units:




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o Standard units and non standard units
 long time ago, people measured physical quantities by
using different kind of units of measurements
 Nowadays , most scientific measurements are made using
units such as "the meter, the kilogram and the second"
 Much older units of measurement still survive, and some
of them have a distinctly odd history

 According to the chief information officer of
metrication board:-



a) Fathom:-

The distance a Viking
could encompass in
a hug



b) Foot:-

The statue of Henry I, as
the total width of thirty
six cars of barleycorn
lay side by side

c) Acre

The area ploughable in one day by a team of two oxen
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Ahmed Shawky El-Gendy
Cellular#: +201011557162

, Physics IGCSE Class May/June 2021
“General Physics”
d) The gauge of railways "In Britain"

was chosen to be the same as the distance between the wheels of
a Roman chariot.

 Using different units of measurement causes different
measurement results which make the unit not




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Cellular: +201011557162
internationally approved.
 The units that are not internationally approved are called non
standard units.
 In order to make accurate and reliable measurements, it is necessary to
use units of measurement that do not change and can be adopted by
observers all over the world.
 Units that have been internationally approved are called standard
units.




 Numerous kind of measurement can cause several troubles, such as:
1) difficulty in determining the conversion
factor for converting one unit to another one.
2) Requirement in using many measuring
instruments those are appropriate with the units.

 Therefore, since 1960, there has been an
international agreement establishing the
International System of Units or
SI “the abbreviation for the French name,
le systéme International d’Unités”.
 A distinct advantage of the SI system is a decimal
system that makes the system easy to use,
for example:
1 centimeter is equal to 0.01 meter
1 kilogram is equal to 1000 grams

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Ahmed Shawky El-Gendy
Cellular#: +201011557162