CAIE O LEVEL PHYSICS (5054)
SECTION 1
Motion, Forces and Energy
Complete Beginner-Friendly Study Notes
This booklet covers every topic in Section 1 of the CAIE O Level Physics (5054) syllabus, written from
scratch for someone who has never studied physics before. Each topic includes plain-language
explanations, definitions you must know, boxed formulas, worked examples with full working, and a
quick-revision summary.
1.1 Physical Quantities, Units and Measurement Techniques
1.2 Motion (speed, velocity, acceleration, graphs)
1.3 Mass and Weight
1.4 Density
1.5 Forces (effects, Hooke's Law, Newton's Laws, moments)
1.6 Momentum
1.7 Energy, Work and Power
1.8 Pressure
CAIE O Level Physics (5054) | Section 1: Motion, Forces and Energy Page 1 of 22
, How to Use These Notes
• Read each topic in order — later topics (like Momentum and Energy) build on earlier ones (like
Motion and Forces).
• Grey boxes are Definitions — learn these word for word, since exams often ask you to state a
definition.
• Green boxes are Formulas — learn the symbol, the equation, and the correct unit.
• Blue boxes are Worked Examples — cover the answer and try each one yourself first.
• Orange boxes are Key Points — common exam facts and things students often get wrong.
• At the end of every topic there is a short Quick Revision checklist.
CAIE O Level Physics (5054) | Section 1: Motion, Forces and Energy Page 2 of 22
, 1.1 Physical Quantities, Units and Measurement
Physics is the science of measuring the natural world. Before we can study motion, forces or energy,
we need a common language of quantities and units so that measurements made anywhere in the
world mean the same thing to everyone.
Physical Quantities
A physical quantity is anything that can be measured and expressed as a number together with a unit,
e.g. a length of 5 metres, a mass of 2 kilograms, a time of 10 seconds. A measurement is meaningless
without its unit — saying “the table is 2 long” tells you nothing; you must say “2 metres”.
SI Base Units
Scientists around the world agree to use the International System of Units (SI). In this syllabus you
need to know five base quantities and their SI units:
Quantity SI Unit Symbol
Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Temperature kelvin K
All other units used in mechanics (speed, force, energy, pressure, etc.) are called derived units
because they are built by combining base units, e.g. speed is measured in metres per second (m/s),
which combines the base units of length and time.
Prefixes for Very Large and Very Small Quantities
Because physical quantities can be extremely large or extremely small, we attach a prefix to the unit
instead of writing lots of zeros.
Prefix Symbol Multiplying Factor
giga G × 1,000,000,000 (10■)
mega M × 1,000,000 (10■)
kilo k × 1,000 (103)
deci d ÷ 10 (10■¹)
centi c ÷ 100 (10■2)
milli m ÷ 1,000 (10■3)
micro µ ÷ 1,000,000 (10■■)
nano n ÷ 1,000,000,000 (10■■)
CAIE O Level Physics (5054) | Section 1: Motion, Forces and Energy Page 3 of 22
SECTION 1
Motion, Forces and Energy
Complete Beginner-Friendly Study Notes
This booklet covers every topic in Section 1 of the CAIE O Level Physics (5054) syllabus, written from
scratch for someone who has never studied physics before. Each topic includes plain-language
explanations, definitions you must know, boxed formulas, worked examples with full working, and a
quick-revision summary.
1.1 Physical Quantities, Units and Measurement Techniques
1.2 Motion (speed, velocity, acceleration, graphs)
1.3 Mass and Weight
1.4 Density
1.5 Forces (effects, Hooke's Law, Newton's Laws, moments)
1.6 Momentum
1.7 Energy, Work and Power
1.8 Pressure
CAIE O Level Physics (5054) | Section 1: Motion, Forces and Energy Page 1 of 22
, How to Use These Notes
• Read each topic in order — later topics (like Momentum and Energy) build on earlier ones (like
Motion and Forces).
• Grey boxes are Definitions — learn these word for word, since exams often ask you to state a
definition.
• Green boxes are Formulas — learn the symbol, the equation, and the correct unit.
• Blue boxes are Worked Examples — cover the answer and try each one yourself first.
• Orange boxes are Key Points — common exam facts and things students often get wrong.
• At the end of every topic there is a short Quick Revision checklist.
CAIE O Level Physics (5054) | Section 1: Motion, Forces and Energy Page 2 of 22
, 1.1 Physical Quantities, Units and Measurement
Physics is the science of measuring the natural world. Before we can study motion, forces or energy,
we need a common language of quantities and units so that measurements made anywhere in the
world mean the same thing to everyone.
Physical Quantities
A physical quantity is anything that can be measured and expressed as a number together with a unit,
e.g. a length of 5 metres, a mass of 2 kilograms, a time of 10 seconds. A measurement is meaningless
without its unit — saying “the table is 2 long” tells you nothing; you must say “2 metres”.
SI Base Units
Scientists around the world agree to use the International System of Units (SI). In this syllabus you
need to know five base quantities and their SI units:
Quantity SI Unit Symbol
Length metre m
Mass kilogram kg
Time second s
Electric current ampere A
Temperature kelvin K
All other units used in mechanics (speed, force, energy, pressure, etc.) are called derived units
because they are built by combining base units, e.g. speed is measured in metres per second (m/s),
which combines the base units of length and time.
Prefixes for Very Large and Very Small Quantities
Because physical quantities can be extremely large or extremely small, we attach a prefix to the unit
instead of writing lots of zeros.
Prefix Symbol Multiplying Factor
giga G × 1,000,000,000 (10■)
mega M × 1,000,000 (10■)
kilo k × 1,000 (103)
deci d ÷ 10 (10■¹)
centi c ÷ 100 (10■2)
milli m ÷ 1,000 (10■3)
micro µ ÷ 1,000,000 (10■■)
nano n ÷ 1,000,000,000 (10■■)
CAIE O Level Physics (5054) | Section 1: Motion, Forces and Energy Page 3 of 22
