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Transcript of AQA GCSE PHYSICS ► Seismic Tectonic Main Contents ► PHYSICS Electricity Forces Waves...
AQA GCSE PHYSICS
SeismicTectonic
Main Contents
PHYSICS
ElectricityForces
Waves
Radioactivity
Space
Energy
Voltage
Energy
Mains Cost Charge Control
Graphs
Acceleration
Friction
Moments
Momentum
Circular
Characteristics
Electromagnetic
Optical
Sound
SolarUniverseThermalEfficiency
Resources
Work
Electromagnetism
Induction
Types
Structure
Extras: Electricity, Forces, Waves, Space, Energy, Radioactivity, Links, Terms, Physics
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Electricity Idea map
1
Voltage Energy
Cost
Mains
Charge
Control
Current
Atom
Electron Proton Neutron
Stationary Moving
Electricity Voltage Idea map
Energy Electrons
Circuit
Voltage Current
Components
LDRAmmeter Voltmeter Thermistor
Series Parallel
causes...
1.1
Electricity Voltage Energy and Electrons
• Electricity is fundamentally about 2 things…
• Electrons• Tiny particle• Carry charge• Carry Energy• Effectively Invisible
• Energy• Ability to do• Invisible
Electricity Voltage Current
• Electric Current• Current• Flow of charge• Electricity• Moving Electrons• Symbol I
Mean the same
Small Current 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
Low Voltage
Electricity Voltage Voltage Idea
High Voltage
• Energy per electron• Voltage• Potential Energy• Potential• Symbol V
Mean the same
Low energy Electron High energy Electron
Electricity Voltage Potential Difference
En
ergy
• Potential Energy Difference between 2 points on a wire
• Potential Difference • P.D.• Difference in Voltage• Voltage across
Mean the same
Electricity Voltage Voltmeter
The p.d. across a component in a circuit is measured in volts (V)
A voltmeter connected across (in parallel with) the component.
V
4 Volts
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.
Electricity Voltage Graphing Relationship
• Current-voltage graphs are used to show how the…
• Current through a component varies with the voltage across it.
Voltage
Cu
rren
t
Proportional : As one value increasesso does a second value
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
12 V3 A
Electricity Voltage Series Circuit
• 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
3 A3 A
4 Ω
6 V 6 V
2 Ω2 Ω
Electricity Voltage Parallel Circuit
12 V
12 V
3 A2 A
1 A• 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
12 V
3 A
Electricity Voltage Filament Bulb
• The resistance of a filament lamp increases…• As the temperature of the filament increases.
Res
ista
nce
Temperature
Electricity Voltage Diode
• The current through a diode flows in one direction only.
• The diode has a very high resistance in the reverse direction.
VOLTAGE
CU
RR
EN
T
normal flow
no flow
Electricity Voltage Light Dependent Resistor
• 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…
1000 Ω 10 Ω
Electricity Voltage Thermistor
• A “coldness dependent resistor”• The resistance of a thermistor decreases…• As the temperature increases.• Resists when it is cold
1000 Ω 10 Ω
Electricity Voltage Symbols
V
A
Switch (open) Switch (closed)Cell
Battery
Resistor
Voltmeter
Ammeter
Diode
Variable resistor
Thermistor
L.D.R
Lamp
Fuse
Electricity Energy Ideas map
Voltage
Energy (J) Time (s)
Current
Watt (J per s)Power
1.2 Electrons Coulomb
deliver… in a certain…
to give us…
x
Electricity Energy Electrons carries energy
£2010 J
• This is an electron• It collects energy at the battery…• Travels around a circuit…• And delivers it to a component
Electricity Energy Electrons deliver Energy
• 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.
£30
£20 £10
30 J
20 J 10 J
Bank
Shop Shop
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
10 J10 J
Power = Current x Potential Difference
P = I x V
10 Watts = 2 Amp x 5 Volt
1km
1km
1km
2 cubic kilometres contain about 6 billion billion grains of salt
1km
1km
1km
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.
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
Ability to do
Electrons
Change
Charge per Time
Energy per Charge
Obstacle
Energy per Time
Energy
Charge
Time
Current
Voltage
Resistance
Power
E
Q
t
I
V
R
P
Joule (J)
Coulomb (C)
Second (s)
Amp (A)
Volt (V)
Ohm (Ώ)
Watt (W)
DESCRIPTION NAME SYMBOL UNIT
Electricity Energy Table of 7 key ideas
E Q t
R
V I
P
1 . V = I R
2. E = V Q
3. E = P t
4. Q = I T
5. P = I V
Electricity Energy 7 ideas connected
Electricity Mains Ideas map
Plug Safety
Circuit BreakerLive Fuse
Mains
Types of Current
Direct Alternating
Neutral Earth
1.3
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
Cable grip
Copper Core
Plastic Layer
Plastic Case
Neutral Pin
Fuse
• Brass Pins and Copper Wires are conductors, plastic is an insulator
Live pin
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
• 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.
a.c. d.c.
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
• 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.
12 A
Fuse : 13 A
14 A
Fuse : 13 A
Normal Fault
Electricity Mains Fuse selection
• 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.
3
5
10
13
2
The Goldilocks and the Three
Bears Theory of Fuse Selection™
Melts too soon
Melts too late
Just right
Safe Dangerous
Electricity Mains Circuit Breaker
• 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.
Normal Fault
Safe Current
Weak Magnetic Force
High Current
Strong Magnetic Force
Electricity Mains Earth 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.
Earth WireNo Earth Wire
Exposed Wire
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
Force
Electrolysis
Electrons & Protons
Equal
Attraction
Lack of Electrons Extra Electrons
Force
Neutral PositiveNegative
PrinterPhotocopier
Uses
Electricity Charge Balance of Protons and Electrons
+ -+ -
-+
+ -++
+ -+ -
--
+
-
Equal Lack of Electrons Extra Electrons
Neutral PositiveNegative
Electrons
Protons
• 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
Electricity Charge Multiple Terms
• Charge• Property of Electrons and Protons• Particles which can exert a force• Ability to create movement
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
• 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.
-+ +
+
+
++
+
+ +
++++ +
+
+
+
+
+
+- -
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
--+ +
+
+
++
+
+ +
++++ +
+
+
+
+
+
+- -
-
-
-
-
-
-
-
-
-
-
-
-
-
--
-
-
Positive NegativeNeutral Neutral
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.
A
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
• 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.
1 amp 1 min 2 amps 1 min 2 amps 2 min
Electricity Control Ideas Map
1.6
ProcessorLogic Gates
Sensor
Output device
AND, OR, NOT
Potential Divider
Relay
Capacitor
Time Delay
Variable Resistor
Transistor
Switches
Modifiers
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
• Output devices include:
• Lamps and LEDs (light emitting diode) which produce light• Buzzers which produce sound• Motors which produce movement• Heaters which produce heat
M
Electricity Control Variable Resistor
• The flow of electricity through a circuit (the current) can be controlled by using a fixed or a variable resistor.
PO
TE
NT
IAL
EN
ER
GY
• 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).
Thermistor Variable ResistorV outV in
Electricity Control Potential Divider
0 V
1 V
5 V
4 V
3 V
2 V
0 Ω
1000 Ω
5000 Ω
4000 Ω
3000 Ω
2000 Ω
Electricity Control Equal Resistance
• If the two resistors change by the same amount..• They will continue to share the voltage equally
Vout
0 V
1 V
5 V
4 V
3 V
2 V
0 Ω
1000 Ω
5000 Ω
4000 Ω
3000 Ω
2000 Ω
Electricity Control Unequal Resistance
• It is the proportion of the resistance that is important.• Here the variable resistor setting affects V out.
Vout
Forces Idea Map
2 Fie
ld
Acceleration
Co
nta
ct
Forces
Circular
Momentum
Moments
Friction Gravity
MagnetismMuscular
Around PivotUnbalanced 90o to Motion
Graphs
Changing Velocity
No Acceleration
Balanced
Mass
Constant Velocity
Forces Graphs Summary
Time
Stop
Time
Constant Velocity
Stop
Faster Constant Velocity
Constant Velocity Acceleration
Greater Acceleration
2.1 Graphs
Distance Velocity
Dis
tan
ce (
m)
Vel
oci
ty (
m/s
)
Forces Graphs Distance Time
DIS
TA
NC
E
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 distance-time graph.
Time
Faster Constant Velocity
Constant Velocity
Dis
tan
ce (
m)
Stationary
StationaryConstant Velocity
Faster Constant Velocity
Stationary
Stationary
Forces Graphs Velocity
• The velocity of an object is its speed in a given direction.
Speed: ConstantDirection: Changing
Velocity : Changing
Speed: ConstantDirection: Constant
Velocity : Constant
Forces Graphs Velocity 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..
VE
LO
CIT
Y
TIME TIME TIME
Forces Graphs Acceleration
• 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:
VE
LO
CIT
Y
Time
Velocity Change
TIME
Velocity Change = Acceleration x Time
v - u = a x t
10 m/s = 2 m/s2 x 5 seconds
Forces Graphs Gradient for Speed
• Candidates should be able to calculate the gradient / slope of a distance-time graph.
DIS
TA
NC
E
TIME10
0 km
2 hr
100 km ÷ 2 hr = 50 km/h
Forces Graphs Gradient for Acceleration
• Candidates should be able to calculate:• The gradient of a velocity-time graph and interpret this as acceleration.
VE
LO
CIT
Y
TIME60
m/s
20 sec
60 m/s ÷ 20 sec = 3 m/s2
Forces Graphs Area for Distance
• The area under a velocity-time graph. for an object moving with constant acceleration represents distance travelled.
VE
LO
CIT
Y
6 m/s
5 secV
EL
OC
ITY
15m
6 m/s
5 sec
30m
Forces Acceleration Ideas Map
Newton
F = maAcceleration
Balanced Unbalanced
Forces
Constant Velocity
eg 0 m/s or 10 m/s eg 2 m/s2 or 9 m/s2
2.2
Forces Acceleration Horizontal
AccelerationSpeedDirection
No??
AccelerationSpeedDirection
Yes??
Forces Acceleration Vertical
AccelerationSpeedDirection
No??
AccelerationSpeedDirection
Yes??
Forces Acceleration Constant Motion
• 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.
STOP
Balanced: 0 km/h Balanced: 60 km/h
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
Forces Acceleration Size of Resultant Force
• The greater the force, the greater the acceleration.
VE
LO
CIT
YV
EL
OC
ITY
VE
LO
CIT
Y
Forces Acceleration Effect of Mass
• The bigger the mass of an object… • The greater the force needed to give the object a particular acceleration.
Forces Acceleration Newton
1 kg
1 2 300
1
2
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
Time (sec)
Spe
ed (
m/s
)
Forces Acceleration Falling Objects
4 kg
2 kg1 kg
Forces Acceleration Falling Objects II
Acceleration = Force (Weight) ÷ Mass
a =
40 N
4 kg
=
20 N
2 kg
= 10 N
1 kg
= 10 m/s2
x Gravity (10 N/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.
40 N
4 kg
≠
20 N
2 kg
≠ 1 kg
- 5 N
- 5 N
- 5 N
Forces Acceleration Changing Mass
Masskg
GravityN/kg
WeightN
Distancem
FrictionN
ResultantN
Accelerationm/s2
Times
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
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
0 2 4 6 8 10 12
Forces Acceleration Mass vs Descent Time
Mass (Kg)
Tim
e (s
)
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.
40 N40 N
4 kg
≠ ≠
- 5 N - 10 N
4 kg 4 kg
40 N
- 15 N
Forces Acceleration Changing Friction
Masskg
GravityN/kg
WeightN
Distancem
FrictionN
ResultantN
Accelerationm/s2
Times
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
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
0 100 200 300 400 500 600
Forces Acceleration Friction vs Descent Time
Friction (N)
Tim
e (s
)
Forces Acceleration Time Formula
s = distance travelled u = initial velocity v = final velocity a = acceleration t = time taken
acceleration = velocity change ÷ time
a = v - u ÷ t1. v = u + at
average speed = distance ÷ time2. (u + v) ÷ 2 = s ÷ t1. into 2. (u + u + at) ÷ 2 = s ÷ t
u is zero so…½at = s ÷ t
s = ½at2
2s ÷ a = t2
t = √(2s ÷ a)
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
Friction2.3Fluids Solid
Air Water
Terminal Velocity
Reaction Braking
Stopping
Brakes
Friction = Weight
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
• 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.
friction
Forces Friction Braking
• 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
TIME
SP
EE
D
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.
long stopping distance
short stopping distance
reaction time
braking time
Forces Friction 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)
Stopping time
Spe
ed
• 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.
Forces Friction Terminal Velocity
• 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
time
forc
e
weight
friction
60 m/s 4 m/s
acce
lera
tio
n
term
inal
vel
oci
ty
dec
eler
atio
n
on
gro
un
d
term
inal
vel
oci
ty
Forces Friction Terminal Velocity II
Friction
Weight
Friction = Weight therefore there is no acceleration
Forces Friction Driving
• When a vehicle has a steady speed …• The frictional forces balance the driving force.
driving forcefrictional forces
Forces Momentum Ideas Map
2.5
Momentum
Objects have… Velocity
Mass
x
=
Before Collision
After Collision
Before
After
Before
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
• 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).
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
Forces Momentum Collision Calculation II
• The force, change in momentum and the time taken for the change are related as shown:
• Momentum Change (Impulse) = Force x Time10 Kg m/s = 1,000 N x 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
5.4Work (J)
Energy (J)
Useful Energy Wasted Energy
Gravity
ElasticMovement against force
Friction
Inertia
Power (J/s)
Calculated by
Energy Work Joule
• Energy is measured in joules (J).
Jam
es P
resc
ott
Jo
ule
(18
18 -
188
9)
1 Newton
1 metre
0.0 J
0.2 J
0.4 J
0.6 J
0.8 J
1.0 J
Energy Work Examples
10,000,000,000,000,000,000,000,000 J 100,000,000,000,000,000 J
1,000,000,000,000,000 J 10,000,000,000,000 J 100,000,000 J 1,000 J
100 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
Work = Force x Distance
Gravitational Potential Energy = Weight x Change in Height
GPE = W x Δh
50 J = 10 N x 5 m
10 N
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.
WEIGHT
MASS
Energy Work Mass, Gravity and Weight
MASS
GRAVITY FIELD
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 = ½ m x v²
10 J = 0.5 x 5 kg x 4 (m/s)2
Energy Work Power
• Power (Watts) is a measure of how fast energy is transferred. • The greater the power, the more energy is transferred in a given time
200,000,000 W 500,000 W
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)
800700685545475440400265210125120 083
Activity
playing basketballcycling (21 km/h)climbing stairs (116 steps/min)skating (15 km/h)swimming (1.6 km/h)playing tenniscycling (15 km/h)walking (5 km/h)sitting with attention focusedstanding at restsitting at restsleeping
Radioactivity Ideas Map
6
Uses
Radioactivity
Structure
Atoms
PropertiesTypes
Decay
Radioactivity Types Ideas Map
Gamma
Beta
Alpha
6.1
Uses
Types
Tracer
Measuring
Sterilisation
SourceBackground
SpecificRadioactivity
Half Life
Speed of Decay
Radioactivity Types Atoms
• Iron on Copper The Kanji characters for "atom."
• Every thing is made of atoms
Radioactivity Types Stable vs Unstable
• There are two kinds of atoms…
Stable Unstable: Will emit radiation randomly once
Radioactivity Types Alpha Beta Gamma
PA
PE
R
ALU
MIN
IUM
LEA
D
ALPHA
BETA
GAMMA
2 Protons2 Neutrons
High EnergyElectron
High Frequency Wave
• Unstable atoms emit 3 types of radiation…
Radioactivity Types Sources
• 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.
carpets
loft insulation
Radioactivity Types Ions
• 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.
-1
+1+ 1
-1
+1+ 1
-1
Normal Atom Ion
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
ALPHA
BETA
GAMMA
most dangerous
leastdangerous
most dangerous
leastdangerous
Used as tracer
Radioactivity Types Monitoring 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.
Low Dosage High Dosage
Radioactivity Types Half Life
• 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.
100
50
0
0 14 28
Time (s)
Un
dec
ayed
Ato
ms
Radioactivity Structure Ideas Map
6.2
DatingElement
Fission
Atomic Structure
Isotope
Discovery
Scattering Exp.
Nucleus
Nucleons
Proton Neutron Electron
Type of atom
Radioactivity Structure Relative Size
• 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.
ProtonNeutron Electron
Radioactivity Structure Rutherford Expectation
Lo
rd E
rnes
t R
uth
erfo
rd (
1871
- 1
937)
• 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
gold leafalpha particle source alpha detectors
What they expected….
Radioactivity Structure Rutherford Result
deflection
• What actually happened….
• Conclusion 1 : The plum pudding model must be wrong
straight through
reflected back
Radioactivity Structure Rutherford Conclusion
++
++
• Conclusion 2 : Nuclei are positive and far apart
++
++
++
simplified gold nucleus
Radioactivity Structure Masses
Neutron
Electron
• 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.
Ne+ = 20
= 10
Radioactivity Structure Proton Number
• All atoms of a particular element have the same number of protons.
3 protons therefore Lithium
Radioactivity Structure Elements
• Atoms of different elements have different numbers of protons.
1 proton therefore Hydrogen 2 protons therefore
Helium
3 protons therefore Lithium 4 protons therefore
Berylium
Radioactivity Structure Isotopes
• Atoms of the same element which have different numbers of neutrons are called isotopes.
normalHydrogen 1 extra
neutron
2 extraneutrons 3 extra
neutrons
isotopes of hydrogen
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
• 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.
=3,500,000 g of Coal 1 g of Uranium
Radioactivity Structure Carbon Dating
• The older a particular radioactive material, the less radiation it emits. • This idea can be used to date materials, including rocks.
The tomb of Rameses IX lies in the centre of the Valley of
the Kings
Wooden Bowl dated to 1000 BC
Radioactivity Structure Carbon Dating
• 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.
5,000yr 10,000yr
74%
100%
1,00
0yr
Radioactivity Structure Non-Carbon Dating
58%
15,0
00 y
r
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
ELECTRICITYAlternating currentAmmeterAmpereAnodeBatteryCapacitorCathodeCellChargeCircuit breakerConductorCoreCoulombCurrentDiodeDirect currentDynamoEarthingElectrical energyElectrical chargeElectric currentElectrodeElectrolysisElectrolyteElectromagnetElectromagnetic inductionElectronElectrostatic forcesFree electronFrictionFuseGeneratorHertzInput sensorInsulationInsulatorIonIoniseJouleKilowattKilowatt hourLight-dependent resistorLogic gateMagnetMagnetic fieldMotor effectOhmOutput deviceParallel/series circuitsPotential differencePotential dividerPowerPrimary coilProcessorRelayResistance
FORCEAccelerationAir resistanceBraking distanceCentre of massCentripetal forceDecelerateDragElastic collisionFrictionGravityKinetic energyMassMomentMomentumNewtonPivotSpeedTerminal velocityThinking distance VelocityWeight
WAVESAmplitudeAnalogue signalCompression Converging lensCoreCrestsCritical engleCrustCycleDiffractionDigital signalsDiverging lensElectromagnetic spectrumElectromagnetic wavesFetal imaging FetusFocusFrequencyHertzLithosphereLongitudinal waveMagmaMantleNormalP wavesRarefractionReal imageRefractionSeismic wavesSeismographS wavesSubduction zoneTectonic platesTotal internal reflectionTransverse wavesTroughsUltrasoundVibrationVirtual imageWavelengthWavesWave speed
SPACEArtificial satelliteBig bangBlack holeCometFusionGalaxyGeostationary satelliteGravityLight yearMilky wayMoon OrbitPlanetRed planetRed giantRed shiftSatelliteSolar systemStarSunUniverseWhite dwarf
ENERGYConductionConvectionEfficiencyElastic potential energyElectrical energyFossil fuelsFree electronsGeneratorGeothermal energyGlobal warmingGravitational potential energyGreenhouse effectHydroelectricKinetic energyNon-renewable resourcesPowerRadiationRenewable energyTurbineWork
RADIOACTIVITYActivityAlphaAtomAtomic numberBackground radiationBetaChain reactionCosmic rayCount rateDecayElectronsElectromagnetic spectrumElement GammaGieger-Muller tubeHalf-lifeIoniseIsotopeMass numberNeutronNuclear fissionNucleonNucleusProtonRadiationRadioactive datingRadioactive decayRadioactive emissionsRadioactive tracerRadioactivityRadioisotopesRandom
ResistorSecondary coilSolenoidThermistorTransformerTransistorVoltVoltageVoltmeterWatt
Connections
SeismicTectonic
PHYSICS
Electricity
Forces
Waves
Radioactivity
SpaceEnergy
Voltage
Energy
Mains
Cost
Charge
Control
GraphsAcceleration
Friction
MomentsMomentum
Circular
Characteristics
Electromagnetic Spectrum
Optical
SoundSolar
Universe
Thermal
Efficiency
Resources
Work
Electromagnetism
Induction
Types
Structure
Amplitude
Analogue signal
Compression
Core
Critical angle
Crests
Converging lens
Crust
Digital signals
Diverging lens
Diffraction
Cycle
Focus
Frequency
Fetal imaging
Hertz
Lithosphere
Magma
P waves
Refraction
Mantle
Rarefraction
Normal
Longitudinal
Subduction zone
Total internal reflection
Seismograph
S waves
Real image
Transverse
Troughs
Vibration
Virtual image
Wave speed
Wavelength
Ultrasound
Air resistance
Braking distance
Centre of mass
Centripetal force
Decelerate
Drag
Pivot
Speed
Terminal velocity
Thinking distance
VelocityWeight
Elastic collision
Gravity
Kinetic energy
MassNewton
Artificial satelliteLight year
Big bang
Milky way
Black holeOrbit
Moon
Comet
Planets
FusionRed giant
GalaxyRed shift
GeostationaryPolar
SatelliteStar
Solar system
Sun
White dwarf
Conduction Convection
Elastic potential energy
Electrical energy
Fossil fuels
Generator
Geothermal
Stopping Distance
Direction
HertzInsulation
Input sensor
Insulator
Joule
Kilowatt
Kilowatt hour
Light-dependent resistorLogic gate
Output device
Ohm
Circuits
Potential difference
Potential divider
Power
Processor
RelayResistor
Resistance
Thermistor
Transistor
VoltVoltage
Watt
Voltmeter
Alpha
Atom
Atomic number
Background radiation
Beta
Chain reaction
Cosmic ray
Count rate
Nuclear fission
Nucleon
Nucleus
Proton
Dating
DecayEmissions
Tracer
Electrons
Electromagnetic spectrum
Element
Gamma
Gieger-Muller tube
Half-life
Isotope
Mass number
Neutron
Radioisotopes
Random
Global warming
Gravitational potential energy
Hydroelectric
Greenhouse effect
Kinetic energy
Non-renewable
Power
Renewable Radiation
Turbine
Uses
Magnet
Magnetic field
Motor effect
Primary coil
Secondary coil
Solenoid
Transformer
ATOM small unit of matter
ELECTRON part of atom, can leave
MEASUREMENT what units are used to count electrons
COULOMB a word for a large number of electrons
ABILITY TO MAKE THINGS MOVE charge, there are two types. negative and positive
MOVING ELECTRONS current, flow of charge, electricity
WORDS FOR LARGE NUMBERS are convenient eg the word ‘year’ instead of 31,536,000 seconds
PROPERTIES what features or attributes does an electron have
EFFECTS things that happen because of electrons
STATIONARY ELECTRONS very large numbers of electrons grouped together. static electricity, ’static’, electrostatics
REPELLED move away from other electrons
PROTON part of atom, cannot leave
ATTRACTED move towards protons
EXTRA ELECTRONS negatively charged
ELECTRONS HAVE A NEGATIVE CHARGE sometimes electrons are referred to as ‘charge’.The charge on proton is positive LACK OF ELECTRONS
positively charged
MEASUREMENThow many electrons passing a point
ENERGY electrons can deliver energy
ELECTRONS PER SECONDmeasured in amps
ENERGY DELIVERED PER SECOND measured in watts, joules per second
ENERGY PER ELECTRON measured in volts
- - +-
EASE OF MOVEMENTTYPES OF MOVEMENT
BACKWARDS AND FORWARDS alternating current
ALWAYS ONE WAY direct current
MAINS delivers energy to the home
BATTERY
EASY conductor eg copper
DIFFICULT SOMETIMES DIFFICULT
IMPOSSIBLEinsulator eg plastic
EXCESSIVE ENERGY IS DANGEROUS
DIFFICULTY SET BY USER variable resistor
WHEN COLD thermistor
WHEN DARK light dependent resistor
ENERGY COSTS MONEY
IF 1000 JOULES of energy is delivered per second…
…for 1 HOUR
..the electricity company call it a UNIT or kilowatthour…a unit costs about £0.08
SAFETY MEASURES
INDIRECT CONTROL
DELIBERATE WEAK POINT
AUTOMATIC OFF SWITCH
RELAY a small safe current switches on a big unsafe current
FUSEwhen the current surges a thin section of wire melts
CIRCUIT BREAKER very quick off switch
NORMAL NUMBER OF ELECTRONS no charge, neutral
-+++
- - - - -+++
- -+++
1. Charged objects attract neutral ones2. Positive and negative objects attract3. Like charged objects repel
1. Electrons move round circuits 2. A circuit is a number of components eg bulbs connected by wires3. A battery provides a stream of electrons
WIRE IS THIN
WIRE IS LONG
POOR CONDUCTORfixed resistor
Env
ironm
ent
Dep
ende
nt
-
ELECTRICITY phenomena explained by electrons
SPEED m/s
DISTANCE metres
TIME seconds
DIRECTION
SIZE measured in newtons
EXAMPLES
INCREASE acceleration
DECREASE deceleration
CONSTANT SPEED
D
T
S
T
CHANGING SPEED CHANGING DIRECTION
TEMPORARY FORCE direction changes
CONSTANT FORCE direction always changes
Circular eg ball swung round on a string moon orbiting earth
OBJECTS HAVE...
FORCES ACTING ON THEMBALANCED FORCES
UNBALANCED FORCES
CONSTANT VELOCITY eg 0 m/s or 100 m/s
CHANGING VELOCITY
CHARACTERISTICS how can we describe a force
DIRECTION
CONTACT FORCES muscular, friction
NONCONTACT FORCES field forces. gravity, magnetism
GRAPHS representing motion
CHANGING SPEED
D
T
S
T
VELOCITY
sober, well rested, good brakes, dry road
drunk, tired, bad brakes, icy road
stop
stop
braking
braking
weight
friction
Friction = WeightAcceleration = 0Speed = 60 m/s
Terminal Velocity
Momentum
Mass
FORCE AND MOTION a push or a pull which creates movement
TYPES OF MOVEMENT
OSCILLATION also known as vibration
A to BSIDE TO SIDE UP AND DOWN
KNOCK-ON EFFECTS original movement causes movement elsewhere
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
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
CHANGE SPEED eg moving from air to glass
CHANGE DIRECTION
SPREAD OUT when passing thru a gap: diffraction
OSCILLATION AT 90O
TO DIRECTION OFTRAVELtransverse waves
OSCILLATION IN DIRECTION OFTRAVEL longitundinal waves
Sound SLINKY
EARTHQUAKES
ROPE SEA WAVES ELECTROMAGNETIC300,000 km/s
CAN CARRY INFORMATION analogue or digital
BENDINGlight refracts when it hits glass at an angle
BOUNCING OFF reflection
BENT TOWARDS each other by a convex lens
BENT AWAY FROM each other by a concave lens
MANY PARALLEL WAVES
ISOLATED original movement only
GAMMA X RAY ULTRAVIOLET LIGHT INFRARED MICROWAVE RADIO
SINGLE WAVE
AM
PLI
TU
DE
WAVELENGTH
digital is better because the message is preserved even if the wave is distorted
distorted wave still readable as 1 or 0
WAVES movement of energy but not matter
HISTORY
UNIVERSEeverything we can see
STRUCTURE
OUR GALAXY100 billion stars called the milky way
OTHER GALAXIES100 billion
OUR STAR, THE SUNis orbited by..
8 OTHER PLANETS
Mercury, Venus, (Earth), Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
THE EARTHis orbited by..
SATELLITESobjects held in circular path by earth’s gravity
NATURAL ARTIFICAIL
MOONcauses tides
USES
MONITOR EARTHweather, military
COMMUNICATIONSMONITOR SPACEeg hubble space telescope
TYPES OF ORBIT
APPARENTLY FIXED IN THE SKYgeostationary orbit
MOVES IN THE SKYpolar orbit
STARSmassive nuclear furnaces
ENERGY SOURCE LIFE CYCLE
NUCLEAR FUSIONhydrogen and helium fusing together to create..
HEAT AND LIGHT
HEAVIER ATOMS which make life possibleeg carbon
PASTgravity pulls dust together. fusion begins
PRESENTexpansive nuclear forces = gravity
FUTURE
MEDIUM STAR BIG STAR VERY BIG STAR
STAR SWELLSinto a red giant
STAR EXPLODESsupernova
BLACK HOLE ultra dense, no light escapes
expansive forces win over gravity
PAST PRESENT FUTURE
MASSIVEEXPLOSIONBig Bang
EXPANDING
EVIDENCE FOR EXPANSION
RED SHIFTlight from distance stars has a longer wavelength than we would ‘expect’ if universe were static
CONTRACTION?Big Crunch?
LIFEEvidence for
DIRECT INDIRECT
Chemical changes in atmosphere Eg O2
Finding live or fossilised organisms
Broadcast signals
SPACE universe, galaxy, solar system, star, planet, satellite
ENERGY
CHARACTERISTICS
CANNOT BE DESTROYED
TYPES
POTENTIAL ENERGY stored energy KINETIC ENERGY movement energy
SMALL SCALE can’t seeLARGE SCALE can see SMALL SCALE can’t seeLARGE SCALE can see
BONDS BETWEEN ATOMS chemical
UNSTABLE ATOMS nuclear
MATERIAL UNDER TENSION strain
HEIGHT gravitational potential energy
ATOMS VIBRATING heat or thermal energy
MOVING CAR
ENERGY USEFUL TO HUMANS known as work eg a moving car
maximising the useful energy makes the car EFFICIENT
eg coal, gas, oil, wood
eg water behind dam, sky diver
MEASURED in joules
1. ATOMS COLLIDE WITH THEIR NEIGHBOURS conduction
3. WAVE TRANSMISSION radiation
2. ATOMS MOVE TO A NEW LOCATION convection
VIBRATIONS CAN SPREAD IN 3 WAYS
eg uraniumeg bow and arrow, spring
CANNOT BE CREATED
ENERGY CAN CHANGE TYPErate of change is measured in watts
STORED ENERGY eg petrol is changed into…
ENERGY NOT USEFUL TO HUMANS known as dissipated energy eg heat from car engine
CURRENT CREATES MOVEMENT motor
MOVEMENT CREATES CURRENT generator
ROTATIONof magnet
ELECTRONS FLOWING magnetic field created
F
D
F
D F
D
GREATER FORCE means greater energy
GREATER DISTANCE means greater energy
eg saucepan base
eg warmth from sun
eg boiling water
NS NS N SN S
MAGNET MOVING WIRE MOVING
Creating current without contact (Induction)
ENERGY the ability to make things happen
STRUCTUREwhat is an atom made of
UNSTABLE ATOMSbreak apart, pop, decay RANDOMLYby kicking out (emitting) particles and energy
STABLE ATOMS stay the same forever
ATOMsmall unit of matter
CENTRAL COREnucleus
.
.NUCLEONvery small unit of matter
PROTON
positively charged(exerts a force)
NEUTRON
not charged(exerts no force)
OUTER CLOUD
.ELECTRONsmallest unit of matternegatively charged(exerts a force)
HYDROGEN ATOMSalways have one proton
HELIUM ATOMSalways have two protons
a LITHIUM ATOMalways has three protons
normal atom
isotopes have extra neutrons
proton number
mass number
TYPES OF ATOM elements
STABILITY OF ATOM
2 PROTONS & 2 NEUTRONS EMITTEDalpha radiation
1 ELECTRONEMITTEDbeta radiation
.
HIGH ENERGY WAVE EMITTEDgamma radiation
WHAT ATOMS EMIT
BLOCKED BY(absorbed by)
card
alum
iniu
m
lead
FORMATION
NATURAL
UNNATURAL
bombarded with neutrons
CONTROLLEDnuclear reactor
RAPIDnuclear bomb
HOW UNSTABLE IS THE ATOM?how long does it take for…
Li7
3chemical symbol
ALL ATOMS TO DECAY
HALF THE ATOMS TO DECAY
DIFFICULT TO PREDICT
EASY TOPREDICT
VERY UNSTABLEshort halflife
50%
1ms
VERYSTABLElong halflife
50%
1mil. yr.
DESCRIPTION AND NOTATION
alpha
beta
gamma
alpha
beta
gamma
INS
IDE
BO
DY
skin cell: dead
tissue cell: live
damaged cell
OU
TS
IDE
BO
DY
MEDICAL USE
98%
1%1%
protons inatoms
protons in alpha particleslike charges repel
Rutherford used alpha particle to show that nuclei are far apart
RADIOACTIVITY fast moving particles and high energy waves
Frequency (f) Wavelength (λ)
Gravitational Field Strength (g)
Weight (w)
Change in Height (Δh)
Distance (d)
Force (F)
Acceleration (a)
Power (P)
Charge (Q)Resistance (R)
Time (t)
Voltage (V)
Current (I)
Energy (E)
ELECTRICAL
Unit Cost
Total Cost
Efficiency
Useful Energy
Momentum
Mass (m) Velocity (v)
ELECTRICALWORKKINETICGPE
Moment
Impulse
½ mv2
Links