IGCSE PHYSICS NOTES
Chapter 1 Making Measurements
<1> Physical Quantities
Definition:
【Physical quantity】:
It is a quantity that can be measured.
It consists of magnitude and unit.
<2> Base Physical Quantities
Quantity Symbol of Quantity SI Unit Symbol of SI Unit
length L meter m
mass m kilogram kg
time t second s
temperature T Kelvin K
current I ampere A
<3> Derived Quantities & Units
e.g. velocity [v]=m/s or ms-1
density [ρ]=kg/m3
volume [v]=m3
area [A]=m2
<4> Prefix of Unit
tera- T- 1012
giga- G- 109
mega- M- 106
kilo- k- 103
deci- d- 10-1
centi- c- 10-2
milli- m- 10-3
micro- μ 10-6
nano- n- 10-9
pico- p- 10-12
<5> Measurements of Length
Definition:
【Precision】: smallest division
error: zero error & parallax error
Measuring tape
precision: 0.1cm
range: ≤ 1m
Meter ruler
precision: 0.1cm
range: ≤ 1m
Vernier Calipers
precision: 0.01cm
1
, range: ≤ 15cm
Micrometer Screw Gauge
precision: 0.01mm
range: < 5m
<6> Measurements of Time
Stopwatch / Clock
Simple pendulum
【oscillation】: One complete to and fro motion back and forth
【period】: Time taken for one complete oscillation
【frequency】: Number of oscillations in one second
*T=1/f
*Repeat & Take averaging: count more oscillations
<7> Measurements of Volume
*water displacement
*tool: measuring cylinder
<8> Scalars and Vectors
【scalar】: Only has magnitude
【vector】: Both has magnitude and direction
scalar e.g. length, mass, time, temperature,current, distance, speed
vector e.g. displacement, velocity, acceleration, force, weight, momentum, impulse
Chapter 2 Describing Motion
<1> Distance & Displacement
【Distance】: a scalar, the total length of actual path moved by an object
unit: meter
【Displacement】: a vector, the distance moved by an object in a specific direction
unit: meter
<2> Speed & Velocity
【Speed】: Speed = distance moved / time taken
【Velocity】: Velocity = displacement moved / time taken
【Average velocity】: Average velocity = total displacement moved / total time taken
【Instantaneous velocity】: v = ds / dt
<3> Acceleration
【Acceleration】: Rate of change in velocity
acceleration (a) = change of velocity / change of time
If a > 0, the object speeds up;
If a = 0, the object moves in constant velocity;
If a < 0, the object slows down.
<4> Graph of Motion
Distance - time graph
2
, Velocity - time graph
<5> Free Fall
Acceleration due to free fall is 9.8ms-2 when air resistance is negligible. ( g=9.8ms-2)
Chapter 3 Forces and Motion
<1> Mass
【mass】:
It is the amount of matter in an object.
It is a property that resists a change in its motion.
<2> Weight
【weight】: It is a gravitational force on object due to gravitational field.
<3> Gravitational Field
【gravitational field】: It is a region in which an object experiences a gravitational force.
<4> W, m relationship
W=mg, g is gravitational field strength acceleration of free fall
<5> Common instruments to measure mass & weight
Mass: beam balance
Weight: spring balance
<6> Inertia
Inertia only depends on mass.
The larger the mass, the greater its inertia.
<7> Density
3
, 【density】: Density = mass per unit volume
Common density of matters:
ρwater = 1.0 x 10-3 kgm-3
ρice = 0.9 x 10-3kgm-3
ρoil = 0.8 x 10-3kgm-3
ρmercury = 13.6 x 10-3 kgm-3
ρcopper = 8.9 x 10-3kgm-3
ρiron = 7.9 x 10-3kgm-3
ρair = 1.29 kgm-3
How to measure density?
a. Measuring density of a regular object
`Step 1: Measure the mass of the object using beam balance.
`Step 2: Use a ruler/vernier calipers to measure length, width and height by volume
formula.
`Step 3: Use ρ=m/v to obtain velocity.
b. Measuring density of an irregular object
`Step 1: Measure the mass of the object using beam balance.
`Step 2: Pour water into measuring cylinder first and record the initial reading, V1.
`Step 3: Place the irregular object into the water and record the final reading V2.
`Step 4: By ρ=m/(V2-V1) to obtain the density.
c. Wood density
attach weight to wood
*Precaution to make the readings as accurate as possible
1) View the scale perpendicular to the cylinder
2) View the scale at the bottom of meniscus
3) Repeat volume measurement and take averaging
*If an object floats on a liquid, then the object has lower density than liquid;
*If an object submerges/sinks to the bottom of a liquid, then tha object has higher
density than liquid.
<8> Force
Effect of Force
1) accelerate / decelerate a moving object
2) change the direction of a moving object
3) change the shape or the size f an object
Force & Motion
【Newton’s 1st law of motion】: Every object continues at constant velocity or at rest
unless acted by a resultant force.
【Newton’s 2nd law of motion】: When a resultant force acts on an object, the object
will accelerate in the direction of the resultant force. The product of mass and
acceleration gives the resultant force.
*Fnet = ma, where Fnet is the resultant force.
【Newton’s 3rd law of motion】: If an object A exerts a force on object B, then object B
exerts an equal and opposite force on object A.
*Forces occur in pairs.
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Chapter 1 Making Measurements
<1> Physical Quantities
Definition:
【Physical quantity】:
It is a quantity that can be measured.
It consists of magnitude and unit.
<2> Base Physical Quantities
Quantity Symbol of Quantity SI Unit Symbol of SI Unit
length L meter m
mass m kilogram kg
time t second s
temperature T Kelvin K
current I ampere A
<3> Derived Quantities & Units
e.g. velocity [v]=m/s or ms-1
density [ρ]=kg/m3
volume [v]=m3
area [A]=m2
<4> Prefix of Unit
tera- T- 1012
giga- G- 109
mega- M- 106
kilo- k- 103
deci- d- 10-1
centi- c- 10-2
milli- m- 10-3
micro- μ 10-6
nano- n- 10-9
pico- p- 10-12
<5> Measurements of Length
Definition:
【Precision】: smallest division
error: zero error & parallax error
Measuring tape
precision: 0.1cm
range: ≤ 1m
Meter ruler
precision: 0.1cm
range: ≤ 1m
Vernier Calipers
precision: 0.01cm
1
, range: ≤ 15cm
Micrometer Screw Gauge
precision: 0.01mm
range: < 5m
<6> Measurements of Time
Stopwatch / Clock
Simple pendulum
【oscillation】: One complete to and fro motion back and forth
【period】: Time taken for one complete oscillation
【frequency】: Number of oscillations in one second
*T=1/f
*Repeat & Take averaging: count more oscillations
<7> Measurements of Volume
*water displacement
*tool: measuring cylinder
<8> Scalars and Vectors
【scalar】: Only has magnitude
【vector】: Both has magnitude and direction
scalar e.g. length, mass, time, temperature,current, distance, speed
vector e.g. displacement, velocity, acceleration, force, weight, momentum, impulse
Chapter 2 Describing Motion
<1> Distance & Displacement
【Distance】: a scalar, the total length of actual path moved by an object
unit: meter
【Displacement】: a vector, the distance moved by an object in a specific direction
unit: meter
<2> Speed & Velocity
【Speed】: Speed = distance moved / time taken
【Velocity】: Velocity = displacement moved / time taken
【Average velocity】: Average velocity = total displacement moved / total time taken
【Instantaneous velocity】: v = ds / dt
<3> Acceleration
【Acceleration】: Rate of change in velocity
acceleration (a) = change of velocity / change of time
If a > 0, the object speeds up;
If a = 0, the object moves in constant velocity;
If a < 0, the object slows down.
<4> Graph of Motion
Distance - time graph
2
, Velocity - time graph
<5> Free Fall
Acceleration due to free fall is 9.8ms-2 when air resistance is negligible. ( g=9.8ms-2)
Chapter 3 Forces and Motion
<1> Mass
【mass】:
It is the amount of matter in an object.
It is a property that resists a change in its motion.
<2> Weight
【weight】: It is a gravitational force on object due to gravitational field.
<3> Gravitational Field
【gravitational field】: It is a region in which an object experiences a gravitational force.
<4> W, m relationship
W=mg, g is gravitational field strength acceleration of free fall
<5> Common instruments to measure mass & weight
Mass: beam balance
Weight: spring balance
<6> Inertia
Inertia only depends on mass.
The larger the mass, the greater its inertia.
<7> Density
3
, 【density】: Density = mass per unit volume
Common density of matters:
ρwater = 1.0 x 10-3 kgm-3
ρice = 0.9 x 10-3kgm-3
ρoil = 0.8 x 10-3kgm-3
ρmercury = 13.6 x 10-3 kgm-3
ρcopper = 8.9 x 10-3kgm-3
ρiron = 7.9 x 10-3kgm-3
ρair = 1.29 kgm-3
How to measure density?
a. Measuring density of a regular object
`Step 1: Measure the mass of the object using beam balance.
`Step 2: Use a ruler/vernier calipers to measure length, width and height by volume
formula.
`Step 3: Use ρ=m/v to obtain velocity.
b. Measuring density of an irregular object
`Step 1: Measure the mass of the object using beam balance.
`Step 2: Pour water into measuring cylinder first and record the initial reading, V1.
`Step 3: Place the irregular object into the water and record the final reading V2.
`Step 4: By ρ=m/(V2-V1) to obtain the density.
c. Wood density
attach weight to wood
*Precaution to make the readings as accurate as possible
1) View the scale perpendicular to the cylinder
2) View the scale at the bottom of meniscus
3) Repeat volume measurement and take averaging
*If an object floats on a liquid, then the object has lower density than liquid;
*If an object submerges/sinks to the bottom of a liquid, then tha object has higher
density than liquid.
<8> Force
Effect of Force
1) accelerate / decelerate a moving object
2) change the direction of a moving object
3) change the shape or the size f an object
Force & Motion
【Newton’s 1st law of motion】: Every object continues at constant velocity or at rest
unless acted by a resultant force.
【Newton’s 2nd law of motion】: When a resultant force acts on an object, the object
will accelerate in the direction of the resultant force. The product of mass and
acceleration gives the resultant force.
*Fnet = ma, where Fnet is the resultant force.
【Newton’s 3rd law of motion】: If an object A exerts a force on object B, then object B
exerts an equal and opposite force on object A.
*Forces occur in pairs.
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