IGCSE Physics Physical Quantities
Physical Quantities and Units
Click the highlighted blanks to reveal the key definitions, examples, and unit conversions.
1 Learning objectives By the end of this section, you will be able to:
• Understand the meaning of the term
________________ physical quantity • Give examples of
________________ physical quantities • State the correct units for recording
________________ physical quantities • Convert between different units of
________________ physical quantities 2 What is a physical quantity? So, what is meant by the words "Physical Quantity" ?
A physical quantity is a
________________ physical property of a material or a system
.
It is a physical property that can be
________________ expressed by measurement
.
A physical quantity can be expressed as a value, which is the algebraic multiplication of a
________________ numerical value and a unit
.
Examples of physical quantities include
________________ mass, length, density, velocity and force
.
3 Units for measuring physical quantities When we take measurements of physical quantities, we need to record them in terms of
________________ units
.
These units are
________________ standardized values
.
Below we shall learn about various units for expressing measurements of physical quantities.
4 Physical quantity: Length Length can be expressed in units such as
________________ millimetre, centimetre, decimetre, kilometre and hectometre
.
(a) 1 kilometre =
________________ 1000 metres (b) 1 metre =
________________ 10 decimetres (c) 1 metre =
________________ 100 centimetres (d) 1 metre =
________________ 1000 millimetres (e) 1 metre =
________________ 0.1 decametres (f) 1 metre =
________________ 0.01 hectometres (g) 1 metre =
________________ 0.001 kilometres 5 Physical quantity: Mass Mass can be expressed in units such as
________________ milligram, centigram, decigram, kilogram and hectogram
.
(a) 1 kilogram =
________________ 1000 grams (b) 1 gram =
________________ 10 decigrams (c) 1 gram =
________________ 100 centigrams (d) 1 gram =
________________ 1000 milligrams (e) 1 gram =
________________ 0.1 decagrams (f) 1 gram =
________________ 0.01 hectograms (g) 1 gram =
________________ 0.001 kilograms 6 Physical quantity: Capacity Capacity can be expressed in units such as
________________ millilitre, centilitre, decilitre, kilolitre and hectolitre
.
(a) 1 kilolitre =
________________ 1000 litres (b) 1 litre =
________________ 10 decilitres (c) 1 litre =
________________ 100 centilitres (d) 1 litre =
________________ 1000 millilitres (e) 1 litre =
________________ 0.1 decalitres (f) 1 litre =
________________ 0.01 hectolitres (g) 1 litre =
________________ 0.001 kilolitres 7 Physical quantity: Time Time can be expressed in units such as
________________ hours, minutes, seconds and days
.
(a) 1 year =
________________ 365 days (b) 1 day =
________________ 24 hours (c) 1 hour =
________________ 60 minutes (d) 1 minute =
________________ 60 seconds (e) 1 second =
________________ 1000 milliseconds (f) 1 day =
________________ 86,400 seconds (g) 1 hour =
________________ 3,600,000 milliseconds
You need to know:
(a) A physical quantity is a measurable property of a material or system.
(b) A physical quantity is written as a number multiplied by a unit.
(c) Examples include length, mass, density, velocity, force, capacity and time.
(d) Standard units must always be used when recording measurements.
(e) You should be able to convert between common units of length, mass, capacity and time.
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