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AQA GCSE PHYSICS ►
Main Contents ►
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Cost
Charge
Mains
Energy
Control
Graphs
Acceleration
Voltage
Friction
Electricity
Forces
Structure
Types
Momentum
Radioactivity
Circular
PHYSICS
Induction
Waves
Energy
Electromagnetism
Moments
Characteristics
Electromagnetic
Work
Optical
Sound
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Resources
Seismic
Efficiency
Thermal
Tectonic
Universe
Solar
Extras: Electricity, Forces, Waves, Space, Energy, Radioactivity, Links, Terms, Physics
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Electricity ► Idea map
1
Atom
Electron
Moving
Stationary
Current
Charge
Voltage
Energy
Proton
Neutron
Mains
Control
Cost
Electricity ► Voltage ► Idea map
1.1
Energy
Electrons
Voltage
causes...
Current
Circuit
Series
Parallel
Ammeter
Components
Voltmeter
Thermistor
LDR
Electricity ► Voltage ► Energy and Electrons
•
Electricity is fundamentally about 2 things…
•
•
•
Energy
Ability to do
Invisible
•
•
•
•
•
Electrons
Tiny particle
Carry charge
Carry Energy
Effectively Invisible
Electricity ► Voltage ► Current
•
•
•
•
•
•
Electric Current
Current
Flow of charge
Electricity
Moving Electrons
Symbol I
Small Current
Mean the same
Large Current
Electricity ► Voltage ► Amps
A
•
The current flowing through a component in a circuit is measured in amperes (A).
•
An ammeter is connected in series with the component.
•
1 Amp = 6 billion billion electrons per second
Electricity ► Voltage ► Voltage Idea
•
•
•
•
•
Energy per electron
Voltage
Potential Energy
Potential
Symbol V
Low Voltage
Low energy Electron
Mean the same
High Voltage
High energy Electron
Electricity ► Voltage ► Potential Difference
•
Mean the same
Energy
•
•
•
•
Potential Energy Difference
between 2 points on a wire
Potential Difference
P.D.
Difference in Voltage
Voltage across
Electricity ► Voltage ► Voltmeter
V
4 Volts
The p.d. across a component in a circuit is measured in volts (V)
A voltmeter connected across (in parallel with) the component.
Electricity ► Voltage ► Relationship Concept
• The next four slides make essentially the same point about the
relationship between current and voltage…
•
•
•
•
•
•
•
•
Relationship
Proportional
Connection
One can be worked out from the other
One causes a change in the other
Link
A formula allows us to calculate a value
Dependent
Mean the same
Electricity ► Voltage ► Voltage needed
• A current will flow through an electrical component (or device)…
• Only if there is a voltage or potential difference (p.d.) across its ends.
Electricity ► Voltage ► More voltage, more current
• The bigger the potential difference across a component…
• The bigger the current that flows through it.
Current
Electricity ► Voltage ► Graphing Relationship
Proportional : As one value increases
so does a second value
Voltage
•
Current-voltage graphs are used to show how the…
•
Current through a component varies with the voltage across it.
Electricity ► Voltage ► V = I R
• The current through a resistor (at constant temperature) is
proportional to the voltage across the resistor.
Voltage
=
Current
x
Resistance
V
=
I
x
R
10 Volts
=
2 Amps
x
5 Ohms
Electricity ► Voltage ► Series Circuit
3A
12 V
3A
3A
6V
6V
2Ω
2Ω
4Ω
•
When components are connected in series:
•
•
•
Their total resistance is the sum of their separate resistances.
The same current flows through each component.
The total potential difference of the supply is shared between them
Electricity ► Voltage ► Parallel Circuit
12 V
3A
12 V
3A
2A
12 V
1A
•
When components are connected in parallel:
•
•
•
The current in the branches equals that leaving the battery
The current may vary from branch to branch
The total potential difference of the supply is same for each branch
Resistance
Electricity ► Voltage ► Filament Bulb
Temperature
• The resistance of a filament lamp increases…
• As the temperature of the filament increases.
CURRENT
Electricity ► Voltage ► Diode
normal flow
VOLTAGE
no flow
• The current through a diode flows in one direction only.
• The diode has a very high resistance in the reverse direction.
Electricity ► Voltage ► Light Dependent Resistor
1000 Ω
•
•
•
•
10 Ω
Could be called “darkness dependent resistor”
The resistance of a light dependent resistor decreases…
As the light intensity increases.
It resists when it is dark…
Electricity ► Voltage ► Thermistor
1000 Ω
•
•
•
•
10 Ω
A “coldness dependent resistor”
The resistance of a thermistor decreases…
As the temperature increases.
Resists when it is cold
Electricity ► Voltage ► Symbols
Battery
Cell
Switch (open)
Switch (closed)
Variable resistor
L.D.R
Diode
Fuse
A
Resistor
V
Ammeter
Lamp
Thermistor
Voltmeter
Electricity ► Energy ► Ideas map
1.2
Electrons
deliver…
Coulomb
in a certain…
Energy (J)
Time (s)
to give us…
Power
Voltage
x
Watt (J per s)
Current
Electricity ► Energy ► Electrons carries energy
10 J
•
•
•
•
This is an electron
It collects energy at the battery…
Travels around a circuit…
And delivers it to a component
£20
Electricity ► Energy ► Electrons deliver Energy
£30
30 J
Bank
20 J
10 J
Shop
Shop
£20
£10
• As an electric current flows through a circuit, energy is transferred
• The energy is transferred from the battery or power supply…
•
…to the components in the electrical circuit.
Electricity ► Energy ► Heat from a wire
•
When Charge flows through a resistor, electrical energy is
transferred as heat.
Electricity ► Energy ► Energy per Time
Electricity ► Energy ► Power
• Power is energy transferred per second
• Power is measured in Joules per Second known as a Watt
• 1 Watt = 1 J of energy in 1s
Power
=
Current
x
Potential Difference
P
=
I
x
V
10 Watts
=
2 Amp
x
5 Volt
10
10 J
J
Electricity ► Energy ► Coulomb
• Seconds are inconveniently small to measure the age of a person.
• We use a word which means 31,536,000 seconds.
• The word is year.
• Electrons are inconveniently small to measure everyday numbers of electrons.
• We use a word which means 6,000,000,000,000,000,000 electrons
• The word is Coulomb.
1km
1km
1km
1km
1km
1km
2 cubic kilometres contain about 6 billion billion grains of salt
Electricity ► Energy ► E = VQ
• The higher the voltage of a supply…
• the greater the amount of energy transferred for…
• a given amount of charge which flows.
Energy
=
Potential Difference
x
Charge
E
=
V
x
Q
10 Joules
=
5 Volts
x
2 Coulombs
Electricity ► Energy ► Q = I t
…For 5 Seconds…
3 Coulombs / Sec
(3 Amps)
Equals 15 Coulombs
Charge
=
Current
x
Time
Q
=
I
x
t
15 Coulombs
=
3 Amps
x
5 seconds
Electricity ► Energy ► Table of 7 key ideas
DESCRIPTION
NAME
SYMBOL
UNIT
Ability to do
Energy
E
Joule (J)
Electrons
Charge
Q
Coulomb (C)
Change
Time
t
Second (s)
Charge per Time
Current
I
Amp (A)
Energy per Charge
Voltage
V
Volt (V)
Energy per Time
Power
P
Watt (W)
Obstacle
Resistance
R
Ohm (Ώ)
Electricity ► Energy ► 7 ideas connected
R
1.V=IR
I
V
E
Q
2. E = V Q
t
3. E = P t
4. Q = I T
5. P = I V
P
Electricity ► Mains ► Ideas map
1.3
Types of Current
Direct
Alternating
Mains
Plug
Live
Neutral
Safety
Earth
Fuse
Circuit Breaker
Electricity ► Mains ► Mains voltage
• The UK mains supply is about 230 volts.
• Mains can kill if it is not used safely.
Electricity ► Mains ► Plug
Earth pin
Copper Core
Plastic Layer
Fuse
Live pin
Plastic Case
Neutral Pin
Cable grip
• Brass Pins and Copper Wires are conductors, plastic is an insulator
Electricity ► Mains ► Alternating Current
• An alternating current (a.c.) is one which is constantly changing
direction.
• Mains is an a.c. supply.
• In the UK it has a frequency of 50 cycles per second or 50 hertz
(Hz) which means that it changes direction and back again 50
times each second.
Electricity ► Mains ► Direct Current
• Cells and batteries supply a current which always flows
in the same direction.
• This is called a direct current (d.c.).
Electricity ► Mains ► Oscilloscope Trace
a.c.
d.c.
•
Candidates should be able to compare the voltages of d.c.
supplies…
•
And the frequencies and peak voltages of a.c. supplies from
diagrams of oscilloscope traces.
Electricity ► Mains ► Safety
• If a fault in an electrical circuit or an appliance causes too great
a current to flow, the circuit is switched off by a
• fuse
• or a circuit breaker.
Electricity ► Mains ► Fuse
Normal
Fault
14 A
12 A
Fuse : 13 A
Fuse : 13 A
• When the current through a fuse wire exceeds the current rating
of the fuse..
• The wire becomes hot and will (eventually) melt breaking the
circuit and switching off the current.
Electricity ► Mains ► Fuse selection
Melts too late
13
The Goldilocks and the Three
Bears Theory of Fuse Selection™
10
Just right
5
Melts too soon
3
2
Safe
Dangerous
• The fuse should have a value higher than, but as close as possible
to, the current through the appliance when it is working normally.
• The manufacturer will normally recommend a fuse.
Electricity ► Mains ► Circuit Breaker
Normal
Weak Magnetic Force
Safe Current
Fault
Strong Magnetic Force
High Current
•
A circuit breaker uses an electromagnet to detect a surge and
operate a very quick automatic off switch.
•
When the fault is fixed the circuit breaker can be reset.
Electricity ► Mains ► Earth Wire
No Earth Wire
Earth Wire
Exposed Wire
• Appliances with metal cases need to be earthed.
• The earth pin is connected to the case via the yellow/green wire.
• If a fault in the appliance connects the case to the live wire, and the
supply is switched on, a very large current flows to earth and
overloads the fuse.
Electricity ► Mains ► Live Wire
• The live terminal of the mains
supply alternates between a
positive and negative voltage
with respect to the neutral
terminal.
• The neutral terminal stays at a
voltage close to zero with
respect to earth.
Electricity ► Charge ► Idea Map
1.5
Electrons & Protons
Extra Electrons
Equal
Lack of Electrons
Negative
Neutral
Positive
Force
Force
Attraction
Uses
Photocopier
Electrolysis
Printer
Electricity ► Charge ► Balance of Protons and Electrons
Electrons
Protons
+ + + -
+ + + -
+
+
+ -
Extra Electrons
Equal
Lack of Electrons
Negative
Neutral
Positive
Electricity ► Charge ► Multiple Terms
•
•
•
•
Charge
Property of Electrons and Protons
Particles which can exert a force
Ability to create movement
Mean the same
•
•
•
•
•
•
•
Stationary Electrons
Electrostatics
Static Electricity
Static
Trillions of Electrons ‘flooding in’
Trillions of Electrons leaving an area
The balance between Electrons and Protons
Mean the same
•
•
Negatively Charged: Extra Electrons
Positively Charged: Electrons missing
Both Electrically Charged
Electricity ► Charge ► Phenomena
•
When certain different insulating materials are rubbed against each
other they become electrically charged.
•
Electrically charged objects attract small objects placed near to
them.
Electricity ► Charge ► Charges cause Repulsion and
Attraction
+ + -
+
+ -
+ + •
•
•
•
- +
- +
When two electrically charged objects are brought close together,
they exert a force on each other.
These observations can be explained in terms of two types of charge
called positive (+) and negative (-).
Two objects which have the same type of charge repel.
Two objects which have different types of charge attract.
Electricity ► Charge ► Charge is conserved
Neutral
Positive
+ - + + +
-+
- + +- + + + +
- - - - + - +
+
-+ - +
+
- + - - + -+
Neutral
Negative
+ - + + +
-+
- + +- + + + +
- - - - + - +
+
-+ - +
+
- + - - + -+
•
When two different materials are rubbed against each other,
electrons, which have a negative charge, are rubbed off one material
on to the other.
•
The material which gains electrons becomes negatively charged. the
material which loses electrons is left with an equal positive charge.
Electricity ► Charge ► Discharge
•
A charged conductor can be discharged by connecting it to earth
with a conductor.
Electricity ► Charge ► Sparks
•
The greater the charge on an isolated object, the greater the voltage
(potential difference) between the object and earth.
•
If the voltage becomes high enough, a spark may jump across the
gap between the object and any earthed conductor which is brought
near it.
Electricity ► Charge ► Safety
• Refuelling can be
dangerous because a
spark could ignite the
fumes.
• A wire is used to conduct
the electrostatic charge
away safely (discharging).
Electricity ► Charge ► Metal
•
Metals are good conductors of electricity because some of the
electrons from their atoms can move freely throughout the metal
structure.
Electricity ► Charge ► Photocopier
•
•
•
•
•
•
•
Copying plate is electrically charged.
An image of the page you want to copy is projected on to the plate.
Where light falls on the plate, the Charge leaks away.
The parts of the plate that are still charged attract bits of black powder.
The black powder is transferred from the plate to a sheet of paper.
The paper is heated to make the black powder stick.
There is now a copy of the original page.
A
Electricity ► Charge ► Electrolysis
•
In solid conductors, an electric current is a
flow of electrons.
•
When some chemical compounds are
melted or dissolved in water they conduct
electricity.
•
These compounds are made up of
electrically charged particles called ions.
•
The current is due to negatively charged
ions moving to the positive terminal
(electrode) and the positively charged ions
moving to the negative electrode.
•
Simpler substances are released at the
terminals (electrodes). This process is
called electrolysis.
Electricity ► Charge ► Electrolysis Deposition
1 amp 1 min
2 amps 1 min
2 amps 2 min
•
During electrolysis the mass and/or volume of the substance
deposited or released at the electrode increases in proportion to:
•
•
The current.
The time for which the current flows.
Electricity ► Control ► Ideas Map
1.6
Sensor
Capacitor
Modifiers
Variable Resistor
Potential Divider
Switches
Relay
Transistor
Logic Gates
Processor
AND, OR, NOT
Output device
Time Delay
Electricity ► Control ► Electronic Systems
• Electronic systems have:
• Input sensors which detect changes in the environment.
• A processor which decides what action is needed.
• An output device creates a signal or action.
Electricity ► Control ► Input Sensors
• Input sensors include:
• Thermistors which detect changes in temperature
• LDRs which detect changes in light
• Switches which respond to pressure, tilt, magnetic fields or moisture.
Electricity ► Control ► Output Devices
M
• Output devices include:
•
•
•
•
Lamps and LEDs (light emitting diode) which produce light
Buzzers which produce sound
Motors which produce movement
Heaters which produce heat
Electricity ► Control ► Variable Resistor
•
The flow of electricity through a circuit (the current) can be
controlled by using a fixed or a variable resistor.
POTENTIAL ENERGY
Electricity ► Control ► Potential Divider
V in
•
•
•
Thermistor
Variable Resistor
V out
The voltage that is supplied to the potential divider V in ….
is shared across the two resistors.
If either resistance is increased (or reduced), the share of the voltage across it
also increases (or reduces).
Electricity ► Control ► Equal Resistance
•
•
5000 Ω
5V
4000 Ω
4V
3000 Ω
3V
2000 Ω
2V
1000 Ω
1V
0Ω
0V
If the two resistors change by the same amount..
They will continue to share the voltage equally
Vout
Electricity ► Control ► Unequal Resistance
•
•
5000 Ω
5V
4000 Ω
4V
3000 Ω
3V
2000 Ω
2V
1000 Ω
1V
0Ω
0V
Vout
It is the proportion of the resistance that is important.
Here the variable resistor setting affects V out.
Friction
Gravity
Field
2
Contact
Forces ► Idea Map
Muscular
Magnetism
Forces
Balanced
Unbalanced
Around Pivot
90o to Motion
No Acceleration
Acceleration
Moments
Circular
Constant Velocity
Changing Velocity
Graphs
Momentum
Mass
Forces ► Graphs ► Summary
2.1
Graphs
Distance
Velocity
Faster Constant Velocity
Constant Velocity
Time
Constant Velocity
Velocity (m/s)
Distance (m)
Stop
Greater Acceleration
Acceleration
Stop
Time
DISTANCE
Forces ► Graphs ► Distance Time
TIME
TIME
TIME
Distance
=
Speed
x
Time
d
=
s
x
t
24 km
=
6 km/h
x
4 hours
Forces ► Graphs ► Distance II
•
•
•
On a distance-time graph :
Stationary objects are
represented by horizontal
lines
Objects moving with a
steady speed are
represented by sloping
straight lines.
The steeper the slope of the
graph, the greater the speed
it represents.
If an object moves in a
straight line, how far it is
from a certain point can be
represented by a distancetime graph.
Stationary
Distance (m)
•
•
Faster Constant
Velocity
Constant Velocity
Stationary
Time
Forces ► Graphs ► Velocity
Speed: Constant
Direction: Constant
Speed: Constant
Direction: Changing
•
Velocity : Changing
The velocity of an object is its speed in a given direction.
Velocity : Constant
VELOCITY
Forces ► Graphs ► Velocity Time
TIME
•
•
•
•
TIME
TIME
Velocity-time graphs can represent the motion of a body.
The steeper the slope of the graph, the greater the acceleration it represents
Constant velocity it is represented by a horizontal line.
Constant acceleration it is represent by a straight sloping line..
VELOCITY
Forces ► Graphs ►Acceleration
Velocity Change
Time
TIME
• The acceleration of an object is the rate at which its velocity changes.
• For objects moving in a straight line with a steady acceleration, the
acceleration, the change in velocity and the time taken for the change are
related as shown:
Velocity Change
=
Acceleration
x
Time
v-u
=
a
x
t
10 m/s
=
2 m/s2
x
5 seconds
DISTANCE
Forces ► Graphs ► Gradient for Speed
100 km
100 km ÷ 2 hr = 50 km/h
2 hr
TIME
• Candidates should be able to calculate the gradient / slope of a distancetime graph.
VELOCITY
Forces ► Graphs ► Gradient for Acceleration
60 m/s
60 m/s ÷ 20 sec = 3 m/s2
20 sec
TIME
• Candidates should be able to calculate:
• The gradient of a velocity-time graph and interpret this as acceleration.
Forces ► Graphs ► Area for Distance
6 m/s
30m
5 sec
VELOCITY
VELOCITY
6 m/s
15m
5 sec
• The area under a velocity-time graph. for an object moving with constant
acceleration represents distance travelled.
Forces ► Acceleration ► Ideas Map
2.2
Forces
Newton
Balanced
Unbalanced
Constant Velocity
Acceleration
eg 0 m/s or 10 m/s
eg 2 m/s2 or 9 m/s2
F = ma
Forces ► Acceleration ► Horizontal
Acceleration
Speed
Direction
No
?
?
Acceleration
Speed
Direction
Yes
?
?
Forces ► Acceleration ► Vertical
Acceleration
Speed
Direction
No
?
?
Acceleration
Speed
Direction
Yes
?
?
Forces ► Acceleration ► Constant Motion
STOP
Balanced: 0 km/h
Balanced: 60 km/h
• Balanced forces will have no effect on the movement of an object:
• It will remain stationary or,
• If it is already moving it will continue to move at the same speed and in the
same direction.
Forces ► Acceleration ► Balanced Forces
•
•
•
•
•
The forces acting on an object may cancel each other out
(balance).
When an object rests on a surface:
The weight of the object exerts a downward force on the surface
The surface exerts an upwards force on the object
The sizes of the two forces are the same
Forces ► Acceleration ► Unbalanced Forces
• If the forces acting on an object do not cancel each other out…
• An unbalanced force will act on the object.
Forces ► Acceleration ► Scenarios
• A stationary object will
start to move in the
direction
of
the
unbalanced force
• An object moving in
the direction of the
force will speed up
• An object moving in
the opposite direction
to the force will slow
down
VELOCITY
VELOCITY
VELOCITY
Forces ► Acceleration ► Size of Resultant Force
•
The greater the force, the greater the acceleration.
Forces ► Acceleration ► Effect of Mass
• The bigger the mass of an object…
• The greater the force needed to give the object a particular acceleration.
Speed (m/s)
Forces ► Acceleration ► Newton
1 kg
3
2
1
0
0
1
2
Time (sec)
3
• One newton is the force needed to give a mass of one kilogram an
acceleration of one metre per second squared.
• Force, mass and acceleration are related as shown:
Force
=
Mass
x
Acceleration
F
=
m
x
a
100 Newton
=
2 Kg
x
50 m/s2
Forces ► Acceleration ► Falling Objects
4 kg
2 kg
1 kg
Forces ► Acceleration ► Falling Objects II
Acceleration
=
Force (Weight)
÷
Mass
x Gravity (10 N/kg)
40 N
20 N
10 N
a=
=
= 10 m/s2
=
2 kg
1 kg
4 kg
• Therefore, all objects fall at the same
speed irrespective of mass
• (if we ignore air resistance, Friction)
Forces ► Acceleration ► Effect of Friction
• Air Friction changes the situation
• Acceleration = Resultant Force (Weight – Friction) ÷ Mass
• Friction makes some of the weight effectively unavailable.
-5N
40 N
-5N
20 N
-5N
≠
≠
2 kg
4 kg
1 kg
Forces ► Acceleration ► Changing Mass
Mass
kg
Gravity
N/kg
Weight
N
Distance
m
Friction
N
Resultant
N
Acceleration
m/s2
Time
s
1
10
10
2
5
5
5.00
0.89
2
10
20
2
5
15
7.50
0.73
3
10
30
2
5
25
8.33
0.69
4
10
40
2
5
35
8.75
0.68
5
10
50
2
5
45
9.00
0.67
6
10
60
2
5
55
9.17
0.66
7
10
70
2
5
65
9.29
0.66
8
10
80
2
5
75
9.38
0.65
9
10
90
2
5
85
9.44
0.65
10
10
100
2
5
95
9.50
0.65
Forces ► Acceleration ► Mass vs Descent Time
0.95
0.90
0.85
Time (s)
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0
2
4
6
Mass (Kg)
8
10
12
Forces ► Acceleration ► Effect of Friction
• If area changes, friction changes (eg Larger Parachute)
• Acceleration = Resultant Force (Weight – Friction) ÷ Mass
• Friction makes some of the weight effectively unavailable.
-5N
- 10 N
- 15 N
40 N
40 N
40 N
≠
4 kg
≠
4 kg
4 kg
Forces ► Acceleration ► Changing Friction
Mass
kg
Gravity
N/kg
Weight
N
Distance
m
Friction
N
Resultant
N
Acceleration
m/s2
Time
s
70
10
700
2
100
600
8.57
0.68
70
10
700
2
150
550
7.86
0.71
70
10
700
2
200
500
7.14
0.75
70
10
700
2
250
450
6.43
0.79
70
10
700
2
300
400
5.71
0.84
70
10
700
2
350
350
5.00
0.89
70
10
700
2
400
300
4.29
0.97
70
10
700
2
450
250
3.57
1.06
70
10
700
2
500
200
2.86
1.18
70
10
700
2
550
150
2.14
1.37
Forces ► Acceleration ► Friction vs Descent Time
1.50
1.40
1.30
1.20
Time (s)
1.10
1.00
0.90
0.80
0.70
0.60
0.50
0
100
200
300
Friction (N)
400
500
600
Forces ► Acceleration ► Time Formula
1.
2.
1. into 2.
acceleration
a
v
= velocity change ÷
=
v-u
÷
=
u
+
time
t
at
average speed =
(u + v) ÷ 2
=
(u + u + at) ÷ 2 =
distance
s
s
÷
÷
÷
time
t
t
u is zero so…
½at
=
s
=
2s ÷ a
=
s
½at2
t2
÷
t
t
=
√(2s ÷ a)
s = distance travelled u = initial velocity v = final velocity a = acceleration t = time taken
Forces ► Acceleration ► Equal and Opposite
•
Whenever two bodies interact…
•
The forces they exert on each other are equal and opposite.
Forces ► Acceleration ► Unbalanced Forces
•
If the surface is not strong enough… we have a problem.
Forces ► Friction ► Ideas Map
2.3
Friction
Fluids
Air
Solid
Water
Brakes
Reaction
Braking
Friction = Weight
Stopping
Terminal Velocity
Forces ► Friction ► Types
• A force of friction acts
• When an object moves through air or water
• When solid surfaces slide (or tend to slide) across each other.
Forces ► Friction ► Effects
friction
•
The direction of this force of friction is always opposite to the
direction in which the object or surface is moving.
•
Friction causes objects to heat up and to wear away at their
surfaces.
•
The friction between solid surfaces is used in brakes which slow
down and stop moving vehicles.
SPEED
Forces ► Friction ► Braking
TIME
• The greater the speed of a vehicle:
• The greater the braking force needed to stop it in a certain distance
• The greater the distance needed to stop it with a certain braking force
Forces ► Friction ► Skidding
•
If too great a braking force is applied…
•
Friction between a vehicle's tyres and the road surface may not be
great enough to prevent skidding.
Forces ► Friction ► Stopping Time
reaction time
Speed
braking time
long stopping distance
short stopping distance
Stopping time
•
•
•
•
•
The overall stopping distance is greater if:
The vehicle is initially travelling faster
The driver's reactions are slower (due to
tiredness, drugs, alcohol)
There are adverse weather conditions
(wet/icy roads, poor visibility)
The vehicle is poorly maintained (e.g. worn
brakes/tyres)
•
•
•
The stopping distance of a
vehicle depends on:
The distance the vehicle travels
during the driver's reaction time.
The distance the vehicle travels
under the braking force.
60 m/s
on ground
terminal velocity
deceleration
terminal velocity
force
acceleration
Forces ► Friction ► Terminal Velocity
weight
friction
4 m/s
time
•
•
The faster an object moves through a gas or a liquid (a fluid) the greater
the force of friction which acts on it. When a body falls:
•
•
•
Initially it accelerates due to the force of gravity
Frictional forces increase until they balance the gravitational forces
The resultant force eventually reaches zero and the body falls at its
terminal velocity
Forces ► Friction ► Terminal Velocity II
Friction
Weight
Friction = Weight
therefore there is no acceleration
Forces ► Friction ► Driving
frictional forces
•
•
driving force
When a vehicle has a steady speed …
The frictional forces balance the driving force.
Forces ► Momentum ► Ideas Map
2.5
Before Collision
Mass
After Collision
x
Before
Velocity
Objects have…
After
=
Before
Momentum
After
Before
After
Forces ► Momentum ► Impact
Question: Would you rather be hit with a heavy or a light object?
Answer: It depends on its speed.
Forces ► Momentum ► Elephant vs Cheetah
• The greater the mass of an object…
• and the greater its speed in a particular direction (its velocity)…
• the more momentum the object has in that direction.
• Momentum has both magnitude (size) and direction.
Forces ► Momentum ► Calculation
Momentum, mass and velocity are related as shown:
Momentum
=
Mass
x
Velocity
960 kg m/s
=
120 kg
x
8 m/s
Forces ► Momentum ► Collision
•
•
•
•
When an object collides with another..
The two objects exert a force on each other.
These forces are equal in size but opposite in direction.
Each object experiences a change in momentum which is equal in
size but opposite in direction.
Forces ► Momentum ► Collision Calculation
2 Kg x 10 m/s
5 Kg x 6 m/s
50 Kg m/s
2 Kg x 5 m/s
5 Kg x 8 m/s
50 Kg m/s
•
•
When a force acts on an object that is moving, or able to move…
A change in momentum occurs.
•
•
•
•
In any collision/explosion…
the momentum after the collision/explosion is the same as…
the momentum before the collision/explosion. (for a particular direction)
Momentum is conserved when no other/external forces act on the
colliding/exploding object(s).
Forces ► Momentum ► Collision Calculation II
•
The force, change in momentum and the time taken for the change
are related as shown:
•
Momentum Change (Impulse)
10 Kg m/s
=
=
Force
1,000 N
x
x
Time
0.01 s
Forces ► Momentum ► Kinetic Energy
• When objects collide, the total kinetic energy after the collision in a
particular direction is normally less than before the collision.
• Elastic collisions are those involving no overall change in kinetic energy
Energy ► Work ► Ideas Map
5.4
Energy (J)
Useful Energy
Power (J/s)
Wasted Energy
Work (J)
Calculated by
Gravity
Movement against force
Elastic
Inertia
Friction
James Prescott Joule (1818 - 1889)
Energy ► Work ► Joule
• Energy is measured in joules (J).
1.0 J
0.8 J
0.6 J
1 metre
0.4 J
0.2 J
0.0 J
1 Newton
Energy ► Work ► Examples
10,000,000,000,000,000,000,000,000 J
100,000,000,000,000,000 J
100 J
1,000,000,000,000,000 J 10,000,000,000,000 J
100,000,000 J
1,000 J
Energy ► Work ► Effect of Force
• When a force moves an object, energy is transferred.
• Energy transferred is also called work
Energy ► Work ► Calculation
Force
Distance
Energy
=
Force
x
Distance
E
=
F
x
d
9,000 J
=
900 N
x
10 m
Energy ► Work ► Gravitational Potential Energy
• Gravitational potential energy
is the energy stored in an
object
• Energy is stored because the
object has been moved against
the force of gravity.
Work
=
Force
x
Distance
Gravitational Potential Energy
=
Weight
x
Change in Height
GPE
=
W
x
Δh
50 J
=
10 N
x
5m
10 N
Energy ► Work ► Mass, Gravity and Weight
MASS
GRAVITY FIELD
WEIGHT
MASS
Force on mass
Amount of matter
Region of influence
Weight
=
Mass
x
Gravity
W
=
m
x
g
10 N
=
1 kg
x
10 N/kg
Energy ► Work ► Elastic Potential Energy
• Elastic potential energy is the
energy stored in an elastic
object.
• Energy is stored when work is
done on the object to change
its shape.
Catapult designed by Leonardo da Vinci
Energy ► Work ► Kinetic Energy
• Kinetic energy is the energy an
object has because of its
movement.
• An object has more kinetic
energy:
• The greater its mass (and
therefore inertia.
• The greater its speed
Kinetic Energy
=
½ Mass
x
Speed²
KE
=
½m
x
v²
10 J
=
0.5 x 5 kg
x
4 (m/s)2
Energy ► Work ► Power
200,000,000 W
500,000 W
• Power (Watts) is a measure of how fast energy is transferred.
• The greater the power, the more energy is transferred in a given time
Energy
=
Power
x
Time
E
=
P
x
t
5,000,000 J
=
500,000 Watts
x
10 s
Energy ► Work ► Power and Human Activity
Power (W)
Activity
800
700
685
545
475
440
400
265
210
125
120
083
playing basketball
cycling (21 km/h)
climbing stairs (116 steps/min)
skating (15 km/h)
swimming (1.6 km/h)
playing tennis
cycling (15 km/h)
walking (5 km/h)
sitting with attention focused
standing at rest
sitting at rest
sleeping
Radioactivity ► Ideas Map
6
Atoms
Decay
Structure
Radioactivity
Types
Properties
Uses
Radioactivity ► Types ► Ideas Map
6.1
Alpha
Types
Beta
Gamma
Background
Radioactivity
Source
Specific
Speed of Decay
Half Life
Measuring
Uses
Sterilisation
Tracer
Radioactivity ► Types ► Atoms
•
•
Every thing is made of atoms
Iron on Copper The Kanji
characters for "atom."
Radioactivity ► Types ► Stable vs Unstable
•
There are two kinds of atoms…
Stable
Unstable:
Will emit radiation randomly once
Radioactivity ► Types ► Alpha Beta Gamma
Unstable atoms emit 3 types of radiation…
2 Protons
ALPHA
2 Neutrons
High Energy
Electron
LEAD
GAMMA
ALUMINIUM
BETA
PAPER
•
High
Frequency
Wave
Radioactivity ► Types ► Sources
loft insulation
carpets
• There are radioactive substances all around us, including in the ground, in
the air, in building materials and in food.
• Radiation also reaches us from space.
• The radiation from all these sources is called background radiation.
Radioactivity ► Types ► Ions
-1
-1
Normal Atom
•
•
•
-1
Ion
When radiation from radioactive materials collides with neutral
atoms or molecules these may become charged (ionised).
When radiation ionises molecules in living cells it can cause
damage, including cancer.
The larger the dose of radiation the greater the risk of cancer.
Radioactivity ► Types ► Ionising Radiation
• Higher doses of ionising radiation can kill cells.
• they are used to kill cancer cells and harmful microorganisms.
Radioactivity ► Types ► Measuring Thickness
•
•
•
As radiation passes through a material it can be absorbed.
The greater the thickness of a material the greater the absorption.
The absorption of radiation can be used to monitor/control the
thickness of materials.
Radioactivity ► Types ► Interaction with Body
least
dangerous
most
dangerous
ALPHA
BETA
GAMMA
most
dangerous
least
dangerous
Used as tracer
Radioactivity ► Types ► Monitoring Dosage
Low Dosage
High Dosage
• Workers who are at risk from radiation often wear a radiation badge to
monitor the amount of radiation they have been exposed to over a
period of time.
• The badge is a small packet containing photographic film.
• The more radiation a worker has been exposed to, the darker the film
is when it has been developed.
Radioactivity ► Types ► Half Life
Undecayed Atoms
100
50
0
0
•
•
•
14
Time (s)
28
The half-life of a radioactive substance:
Is the time it takes for the number of parent atoms in a sample to halve.
Is the time it takes for the count rate from the original substance to fall to
half its initial level.
Radioactivity ► Structure ► Ideas Map
6.2
Atomic Structure
Discovery
Nucleus
Scattering Exp.
Nucleons
Proton
Electron
Neutron
Type of atom
Isotope
Element
Dating
Fission
Radioactivity ► Structure ► Relative Size
Neutron
Proton
Electron
• Atoms have a small central nucleus made up of protons and neutrons
around which there are electrons.
• To scale above nucleus would be size of a grain of sand.
•
The ‘plum pudding’ model of matter said
that atoms were solid and uniformly
positive with specks of negativity.
•
If this was the case even a small thickness
of material should block a stream of alpha
particles.
•
Ernest Rutherford decided to test this idea
Lord Ernest Rutherford
(1871 - 1937)
Radioactivity ► Structure ► Rutherford Expectation
What they expected….
alpha particle source
gold leaf
alpha detectors
Radioactivity ► Structure ► Rutherford Result
•
What actually happened….
straight
through
deflection
reflected back
•
Conclusion 1 : The plum pudding model must be wrong
Radioactivity ► Structure ► Rutherford Conclusion
•
Conclusion 2 : Nuclei are positive and far apart
+
+
+
+
+
+
simplified gold nucleus
Radioactivity ► Structure ► Masses
Electron
Neutron
•
•
•
Kilograms are inconvenient for such tiny masses…
So the Atom Mass Unit was invented.
Protons and neutrons weigh 1 AMU by definition, an electron is 1/2000 AMU
Radioactivity ► Structure ► Notation
+
•
•
•
•
The number of electrons is equal to the number of
protons in the nucleus therefore…
The atom as a whole has no electrical charge.
10 - 10 = 0
The total number of protons and neutrons (nucleons)
in an atom is called its mass (nucleon) number.
=
20
=
10
Ne
Radioactivity ► Structure ► Proton Number
3 protons therefore Lithium
•
All atoms of a particular element have the same number of protons.
Radioactivity ► Structure ► Elements
1 proton therefore
Hydrogen
•
3 protons therefore
Lithium
2 protons therefore
Helium
4 protons therefore
Berylium
Atoms of different elements have different numbers of protons.
Radioactivity ► Structure ► Isotopes
normal
Hydrogen
2 extra
neutrons
1 extra
neutron
3 extra
neutrons
isotopes of hydrogen
•
Atoms of the same element which have different numbers of
neutrons are called isotopes.
Radioactivity ► Structure ► Beta Decay
•
Radioactive isotopes (radioisotopes or radionuclides) are atoms with
unstable nuclei. When an unstable nucleus splits up (disintegrates):
•
•
•
It emits radiation.
A different atom, with a different number of protons, is formed.
For each electron emitted, a neutron in the nucleus becomes a proton.
Radioactivity ► Structure ► Fission
•
Nuclear reactors use a process called nuclear fission. When an
atom with a very large nucleus is bombarded with neutrons:
•
•
The nucleus splits into two smaller nuclei.
Further neutrons are released which may cause further nuclear
fission resulting in a chain reaction.
The new atoms which are formed are themselves radioactive.
•
Radioactivity ► Structure ► Comparative Energies
=
3,500,000 g of Coal
1 g of Uranium
• The energy released by an atom during radioactive disintegration or
nuclear fission is very large compared to the energy released when a
chemical bond is made between two atoms.
Radioactivity ► Structure ► Carbon Dating
The tomb of Rameses IX lies
in the centre of the Valley of
the Kings
•
•
Wooden Bowl dated
to 1000 BC
The older a particular radioactive material, the less radiation it emits.
This idea can be used to date materials, including rocks.
Radioactivity ► Structure ► Carbon Dating
100%
74%
5,000yr
•
•
10,000yr
The half life of Carbon 14 is 5,730 years.
During one half-life, half of the radioactive atoms initially present in
a sample decay. This idea can be used to date materials.
Radioactivity ► Structure ► Non-Carbon Dating
58%
42%
•
•
•
Uranium isotopes, which have a very long half-life, decay via a
series of relatively short-lived radioisotopes to produce stable
isotopes of lead.
The relative proportions of uranium and lead isotopes in a sample
of igneous rock can, therefore, be used to date the rock
The proportions of the radioisotope potassium-40 and its stable
decay product argon can also be used to date igneous rocks from
which the gaseous argon has been unable to escape.
End of main section
► Key Terms
ELECTRICITY
FORCE
WAVES
SPACE
ENERGY
RADIOACTIVITY
Alternating current
Ammeter
Ampere
Anode
Battery
Capacitor
Cathode
Cell
Charge
Circuit breaker
Conductor
Core
Coulomb
Current
Diode
Direct current
Dynamo
Earthing
Electrical energy
Electrical charge
Electric current
Electrode
Electrolysis
Electrolyte
Electromagnet
Electromagnetic induction
Electron
Electrostatic forces
Free electron
Friction
Fuse
Generator
Hertz
Input sensor
Insulation
Insulator
Ion
Ionise
Joule
Kilowatt
Kilowatt hour
Light-dependent resistor
Logic gate
Magnet
Magnetic field
Motor effect
Ohm
Output device
Parallel/series circuits
Potential difference
Potential divider
Power
Primary coil
Processor
Relay
Resistance
Acceleration
Air resistance
Braking distance
Centre of mass
Centripetal force
Decelerate
Drag
Elastic collision
Friction
Gravity
Kinetic energy
Mass
Moment
Momentum
Newton
Pivot
Speed
Terminal velocity
Thinking distance
Velocity
Weight
Amplitude
Analogue signal
Compression
Converging lens
Core
Crests
Critical engle
Crust
Cycle
Diffraction
Digital signals
Diverging lens
Electromagnetic spectrum
Electromagnetic waves
Fetal imaging
Fetus
Focus
Frequency
Hertz
Lithosphere
Longitudinal wave
Magma
Mantle
Normal
P waves
Rarefraction
Real image
Refraction
Seismic waves
Seismograph
S waves
Subduction zone
Tectonic plates
Total internal reflection
Transverse waves
Troughs
Ultrasound
Vibration
Virtual image
Wavelength
Waves
Wave speed
Artificial satellite
Big bang
Black hole
Comet
Fusion
Galaxy
Geostationary satellite
Gravity
Light year
Milky way
Moon
Orbit
Planet
Red planet
Red giant
Red shift
Satellite
Solar system
Star
Sun
Universe
White dwarf
Conduction
Convection
Efficiency
Elastic potential energy
Electrical energy
Fossil fuels
Free electrons
Generator
Geothermal energy
Global warming
Gravitational potential energy
Greenhouse effect
Hydroelectric
Kinetic energy
Non-renewable resources
Power
Radiation
Renewable energy
Turbine
Work
Activity
Alpha
Atom
Atomic number
Background radiation
Beta
Chain reaction
Cosmic ray
Count rate
Decay
Electrons
Electromagnetic spectrum
Element
Gamma
Gieger-Muller tube
Half-life
Ionise
Isotope
Mass number
Neutron
Nuclear fission
Nucleon
Nucleus
Proton
Radiation
Radioactive dating
Radioactive decay
Radioactive emissions
Radioactive tracer
Radioactivity
Radioisotopes
Random
Resistor
Secondary coil
Solenoid
Thermistor
Transformer
Transistor
Volt
Voltage
Voltmeter
Watt
► Connections
Output device
Radioisotopes
Element
Watt
Mass number
Isotope
Atomic number
Nucleon
Background radiation
Potential divider
Potential difference
Nucleus
Transistor
Volt
Ohm
Energy
Resistor
Voltage
Logic gate
Processor
Thermistor
Power
Neutron
Proton
Joule
Kilowatt hour
Light-dependent
resistor
Velocity
Input sensor
Direction
Kilowatt
Insulator
Hertz
Cost
Insulation
Resistance
Electrons
Voltmeter
Mains
Nuclear fission Emissions Decay Atom
Voltage
Structure
Random
Dating
Gieger-Muller tube
Tracer
Circuits
Alpha
Uses
Count rate
Beta
Types
Electricity
Radioactivity
Half-life
Cosmic ray
Gamma
Gravity
Weight
Decelerate
Speed
Relay
Terminal velocity
Air resistance
Graphs
Acceleration
Control
Drag
Braking
distance
Friction
Stopping
Thinking
Distance
distance
Moments
Centre of
Momentum
Circular
mass
Mass
Newton
Pivot
Centripetal force
Chain reaction
Forces
Charge
Cycle
Hertz
Elastic collision Kinetic energy
Troughs
Crests
Wave speed
Secondary coil
Amplitude
Electromagnetic spectrum
Frequency
Wavelength
Generator
Primary coil
Normal
Magnet
Diffraction
Turbine
PHYSICS
Electrical energy
Longitudinal
Transformer
Magnetic field
Refraction
Critical angle
Characteristics
Induction
Motor effect
Solenoid
Transverse
Total internal reflection
Energy
Space
Virtual image
Converging
lens
Electromagnetism
Focus
Waves Optical
Real image
Global warming
Fossil fuels
Big bang
Diverging lens
Ultrasound
Thermal
Fetal imaging
Solar
Resources
Comet
Sound
Greenhouse effect
Non-renewable
Solar system
Rarefraction
Conduction
Convection
Vibration
Universe
Geothermal
Efficiency
Tectonic
Compression
Renewable
Seismic
Radiation
Sun
Magma
Red shift
Crust
Black hole
Hydroelectric
Galaxy
Planets
Gravitational
Core
Lithosphere
Orbit
Work potential energy
Mantle
Electromagnetic
Kinetic energy
Milky way
Subduction
zone
Star
Satellite
Spectrum
Power
Seismograph
Light year
Moon Artificial satellite
Elastic potential
Red giant
Fusion
Geostationary
energy
Digital signals S waves P waves
Polar
White dwarf
Analogue signal
ELECTRICITY ► phenomena explained by electrons
ATOM small unit of matter
ELECTRON part of atom, can leave
PROPERTIES
what features or attributes does an electron have
PROTON part of atom, cannot leave
MEASUREMENT
what units are used to count electrons
EFFECTS
things that happen because of electrons
WORDS FOR LARGE NUMBERS
are convenient eg the word ‘year’
instead of 31,536,000 seconds
MOVING ELECTRONS
current, flow of charge, electricity
ABILITY TO MAKE THINGS MOVE
charge, there are two types. negative and positive
ELECTRONS HAVE A NEGATIVE CHARGE
sometimes electrons are referred to as ‘charge’.
The charge on proton is positive
EXTRA ELECTRONS
negatively charged
COULOMB
a word for a large number of electrons
ATTRACTED
move towards
protons
- -
-
NORMAL NUMBER OF
ELECTRONS
no charge, neutral
- - - - -
- - -
+ + +
+ + +
LACK OF ELECTRONS
positively charged
+ + +
+
1.
2.
3.
MEASUREMENT
how many electrons passing a point
ENERGY
electrons can deliver energy
ELECTRONS PER SECOND
measured in amps
ENERGY PER ELECTRON
measured in volts
Electrons move round circuits
A circuit is a number of components eg bulbs connected by wires
A battery provides a stream of electrons
1. Charged objects attract neutral ones
2. Positive and negative objects attract
3. Like charged objects repel
TYPES OF MOVEMENT
EASE OF MOVEMENT
BACKWARDS AND FORWARDS
alternating current
ALWAYS ONE WAY
direct current
MAINS
delivers energy to the home
BATTERY
EASY
conductor eg copper
ENERGY DELIVERED PER SECOND measured in watts, joules per second
ENERGY COSTS
MONEY
EXCESSIVE ENERGY IS DANGEROUS
IF 1000 JOULES of
energy is delivered per
second…
SAFETY MEASURES
DIFFICULT
SOMETIMES
DIFFICULT
Environment
Dependent
REPELLED
move away from other
electrons
STATIONARY ELECTRONS
very large numbers of electrons grouped together. static electricity, ’static’, electrostatics
IMPOSSIBLE
insulator eg plastic
WHEN DARK
light dependent
resistor
WHEN COLD
thermistor
DIFFICULTY SET BY USER
variable resistor
WIRE IS LONG
…for 1 HOUR
INDIRECT
CONTROL
DELIBERATE WEAK
POINT
AUTOMATIC OFF SWITCH
RELAY
a small safe
current switches
on a big unsafe
current
FUSE
when the current surges
a thin section of wire
melts
CIRCUIT BREAKER
very quick off switch
WIRE IS THIN
..the electricity company
call it a UNIT or
kilowatthour…a unit
costs about £0.08
POOR CONDUCTOR
fixed resistor
FORCE AND MOTION ► a push or a pull which creates movement
OBJECTS HAVE...
VELOCITY
BALANCED FORCES
CHANGING VELOCITY
UNBALANCED FORCES
DIRECTION
SPEED m/s
GRAPHS
representing
motion
TIME
seconds
CHANGING SPEED
CHANGING DIRECTION
EXAMPLES
DISTANCE
metres
INCREASE
acceleration
DECREASE
deceleration
TEMPORARY FORCE
direction changes
CONSTANT SPEED
D
FORCES ACTING ON THEM
CONSTANT VELOCITY eg 0 m/s or 100 m/s
CONSTANT FORCE
direction always
changes
CONTACT
FORCES
muscular,
friction
CHARACTERISTICS
how can we describe a
force
NON►CONTACT
FORCES
field forces. gravity,
magnetism
S
Mass
T
T
CHANGING SPEED
D
Circular
eg ball swung round on a string
moon orbiting earth
SIZE
measured in newtons
DIRECTION
Momentum
Terminal Velocity
S
T
friction
T
weight
braking
stop
sober, well rested, good brakes, dry road
braking
drunk, tired, bad brakes, icy road
stop
Friction = Weight
Acceleration = 0
Speed = 60 m/s
WAVES ► movement of energy but not matter
TYPES OF MOVEMENT
SIDE TO SIDE
UP AND DOWN
A to B
OSCILLATION also known as vibration
KNOCK-ON EFFECTS
original movement
causes movement
elsewhere
ISOLATED
original
movement only
WAVES
CHARACTERISTICS
how do we describe waves
BEHAVIOUR
what do waves do
TYPES
How big is the oscillation?
The AMPLITUDE is 2 metres
How long is the wave from peak to peak?
The WAVELENGTH is 5 metres
CHANGE SPEED
eg moving from air
to glass
SPREAD OUT
when passing thru a
gap: diffraction
CHANGE
DIRECTION
OSCILLATION AT 90O
TO DIRECTION OF
TRAVEL
transverse waves
OSCILLATION IN
DIRECTION OF
TRAVEL
longitundinal waves
How often does a wave pass?
The FREQUENCY is 2 waves per second or 2 hertz
How fast is the wave travelling?
The SPEED of the wave is 10 metres per second
BOUNCING OFF
reflection
Sound
ROPE
SLINKY
SEA WAVES
ELECTROMAGNETIC
300,000 km/s
EARTHQUAKES
MANY PARALLEL WAVES
GAMMA
AMPLITUDE
SINGLE
WAVE
BENDING
light refracts when it hits glass at an
angle
X RAY
ULTRAVIOLET
LIGHT
INFRARED
MICROWAVE
RADIO
CAN CARRY INFORMATION analogue or digital
BENT TOWARDS
each other by a convex lens
BENT AWAY FROM
each other by a concave lens
WAVELENGTH
distorted wave still readable as 1 or 0
digital is better because the message is preserved even if
the wave is distorted
SPACE ► universe, galaxy, solar system, star, planet, satellite
UNIVERSE
everything we can see
HISTORY
STRUCTURE
PAST
PRESENT
FUTURE
MASSIVE
EXPLOSION
Big Bang
EXPANDING
CONTRACTION?
Big Crunch?
LIFE
Evidence for
DIRECT
OUR GALAXY
100 billion stars called the milky way
OTHER GALAXIES
100 billion
Finding live
or fossilised
organisms
INDIRECT
Broadcast
signals
Chemical changes
in atmosphere
Eg O2
EVIDENCE FOR EXPANSION
RED SHIFT
light from distance stars has a longer wavelength
than we would ‘expect’ if universe were static
STARS
massive nuclear furnaces
OUR STAR, THE SUN
is orbited by..
ENERGY SOURCE
THE EARTH
is orbited by..
SATELLITES
objects held in circular path by earth’s gravity
LIFE CYCLE
8 OTHER PLANETS
NUCLEAR FUSION
hydrogen and helium fusing together to create..
Mercury, Venus, (Earth),
Mars, Jupiter, Saturn,
Uranus, Neptune, Pluto
HEAT AND
LIGHT
PAST
gravity pulls dust together.
fusion begins
ARTIFICAIL
MOON
causes tides
USES
FUTURE
HEAVIER ATOMS
which make life possible
eg carbon
MEDIUM STAR
NATURAL
PRESENT
expansive nuclear
forces = gravity
BIG STAR
VERY BIG
STAR
expansive forces win over gravity
TYPES OF ORBIT
STAR SWELLS
into a red giant
MONITOR EARTH
weather, military
MONITOR SPACE
eg hubble space telescope
COMMUNICATIONS
APPARENTLY FIXED IN THE SKY
geostationary orbit
MOVES IN THE SKY
polar orbit
STAR EXPLODES
supernova
BLACK HOLE
ultra dense, no
light escapes
ENERGY ► the ability to make things happen
ENERGY
TYPES
CHARACTERISTICS
POTENTIAL ENERGY stored energy
KINETIC ENERGY movement energy
SMALL SCALE can’t see
LARGE SCALE can see
SMALL SCALE can’t see
LARGE SCALE can see
MEASURED in joules
CANNOT BE DESTROYED
MATERIAL
UNDER
TENSION
strain
HEIGHT
gravitational potential
energy
eg bow and
arrow, spring
eg water behind dam,
sky diver
BONDS BETWEEN
ATOMS
chemical
eg coal, gas, oil,
wood
UNSTABLE
ATOMS
nuclear
MOVING CAR
ROTATION
of magnet
CURRENT
CREATES
MOVEMENT
motor
ELECTRONS
FLOWING
magnetic field
created
ATOMS
VIBRATING
heat or thermal
energy
MOVEMENT
CREATES
CURRENT
generator
eg uranium
CANNOT BE CREATED
ENERGY CAN CHANGE
TYPE
rate of change is measured
in watts
VIBRATIONS CAN SPREAD IN 3 WAYS
F
STORED ENERGY eg petrol is changed into…
D
D
D
F
F
1. ATOMS
COLLIDE WITH
THEIR
NEIGHBOURS
conduction
2. ATOMS MOVE TO A
NEW LOCATION
convection
eg saucepan
base
eg boiling water
3. WAVE
TRANSMISSION
radiation
ENERGY USEFUL TO
HUMANS
known as work
eg a moving car
eg warmth from
sun
ENERGY NOT USEFUL TO
HUMANS
known as dissipated energy
eg heat from car engine
GREATER FORCE means greater energy
maximising the useful energy
makes the car EFFICIENT
GREATER DISTANCE means greater energy
MAGNET MOVING
S
N
Creating current without contact (Induction)
WIRE MOVING
S
N
N
S
N
S
RADIOACTIVITY ► fast moving particles and high energy waves
ATOM
small unit of matter
STABILITY OF ATOM
UNSTABLE ATOMS
break apart, pop, decay RANDOMLY
by kicking out (emitting) particles and energy
.
NUCLEON
very small unit of matter
HOW UNSTABLE IS THE ATOM?
how long does it take for…
.
PROTON
NEUTRON
positively charged
(exerts a force)
not charged
(exerts no force)
ELECTRON
smallest unit of matter
negatively charged
(exerts a force)
.
FORMATION
WHAT ATOMS EMIT
ALL ATOMS
TO DECAY
HALF THE ATOMS
TO DECAY
NATURAL
DIFFICULT
TO PREDICT
EASY
TO
PREDICT
bombarded with neutrons
VERY
UNSTABLE
short half►life
VERY
STABLE
long half►life
CONTROLLED
nuclear reactor
UNNATURAL
RAPID
nuclear
bomb
BLOCKED BY
(absorbed by)
2 PROTONS & 2 NEUTRONS
EMITTED
alpha radiation
1 ELECTRON
EMITTED
beta radiation
.
HIGH ENERGY WAVE EMITTED
gamma radiation
DESCRIPTION AND NOTATION
50%
50%
TYPES OF ATOM elements
1ms
normal atom
1mil. yr.
HYDROGEN ATOMS
always have one proton
MEDICAL USE
isotopes have
extra neutrons
beta
HELIUM ATOMS
always have two protons
Rutherford used alpha particle to show that nuclei are far apart
mass number
proton number
1%
gamma
1%
7
Li
3
98%
chemical
symbol
like charges repel
protons in
atoms
protons in
alpha particles
OUTSIDE BODY
a LITHIUM ATOM
always has three protons
INSIDE BODY
alpha
tissue cell: live
damaged cell
alpha
beta
gamma
skin cell: dead
lead
STABLE ATOMS
stay the same forever
OUTER CLOUD
aluminium
CENTRAL CORE
nucleus
card
STRUCTURE
what is an atom made of
► Links
Frequency (f)
Mass (m)
Gravitational Field
Strength (g)
Wavelength (λ)
Acceleration (a)
Time (t)
Velocity (v)
Momentum
Current (I)
Resistance (R)
Force (F)
v2
Charge (Q)
½m
Weight (w)
Distance (d)
Voltage (V)
Impulse
Change in
Height (Δh)
Moment
Power (P)
GPE
KINETIC
WORK
Energy (E)
Efficiency
Useful Energy
ELECTRICAL
ELECTRICAL
Unit Cost
Total Cost