Physics Paper 1- Higher Tier
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TOPIC 1: ENERGY
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WHAT IS ENERGY?
Definition:
Energy is the capacity to do work or cause change.
Key Fact:
Energy cannot be created or destroyed.
Energy can only be transferred between stores.
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THE 8 ENERGY STORES
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1. KINETIC STORE
Energy an object has because it is moving.
Examples:
- Running person
- Moving car
- Flying football
The faster an object moves, the greater its kinetic energy.
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2. THERMAL (INTERNAL) STORE
Energy an object has because of the movement of its particles.
Examples:
- Hot tea
- Radiator
- Lava
The hotter an object is, the more thermal energy it stores.
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3. GRAVITATIONAL POTENTIAL STORE
Energy an object has because of its position in a gravitational field.
Examples:
- Book on a shelf
- Rollercoaster at the top of a hill
The higher the object, the more gravitational potential energy it has.
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4. ELASTIC POTENTIAL STORE
Energy stored when an object is stretched or compressed.
Examples:
- Stretched spring
- Elastic band
- Bow and arrow
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5. CHEMICAL STORE
Energy stored in chemical bonds.
Examples:
- Food
- Batteries
- Petrol
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6. MAGNETIC STORE
Examples:
- Two magnets attracting
- Two magnets repelling
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7. ELECTROSTATIC STORE
Examples:
- Charged balloon
- Static electricity
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8. NUCLEAR STORE
Examples:
- Nuclear power stations
- The Sun
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ENERGY TRANSFER PATHWAYS
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Energy can be transferred:
1. Mechanically
Using a force.
Example:
A football being kicked.
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2. Electrically
By moving charges.
Example:
Phone charger charging a phone.
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3. By Heating
Thermal energy moves from hot areas to cold areas.
Example:
Hot coffee cooling down.
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4. By Radiation
Energy transferred by waves.
Example:
Sunlight reaching Earth.
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CONSERVATION OF ENERGY
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Exam Definition:
Energy cannot be created or destroyed.
It can only be transferred between stores.
Grade 9 Point:
Do NOT write:
"Energy is lost."
Write:
"Energy is dissipated to the surroundings."
Example:
Light bulb:
Electrical Energy
→ Light Energy
→ Thermal Energy
The thermal energy is usually unwanted.
Formula:
Efficiency = Useful Energy Output ÷ Total Energy Input
Example:
Input Energy = 1000J
Useful Energy = 750J
Efficiency = 750 ÷ 1000
Efficiency = 0.75
Efficiency = 75%
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REDUCING UNWANTED ENERGY TRANSFERS
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Loft Insulation
- Traps air
- Air is a poor conductor
Double Glazing
- Gap between glass panes reduces energy transfer
Cavity Wall Insulation
- Foam fills air gaps
- Reduces energy transfer
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SPECIFIC HEAT CAPACITY
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Definition:
The energy needed to raise the temperature of 1kg of a substance by 1°C.
Formula:
E = mcΔT
E = Energy Transferred (J)
m = Mass (kg)
c = Specific Heat Capacity
ΔT = Temperature Change (°C)
Example:
Mass = 2kg
SHC = 4200
Temperature Change = 5°C
E = 2 × 4200 × 5
E = 42,000J
Grade 9 Point:
Water has a high specific heat capacity.
It heats up slowly and cools down slowly.
V = 4V
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RESISTANCE
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Definition:
Resistance is a measure of how much a component opposes current flow.
Unit:
Ohms (Ω)
Formula:
R = V ÷ I
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FACTORS AFFECTING RESISTANCE
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Longer wire
→ More resistance
Thinner wire
→ More resistance
Higher temperature
→ More resistance
Grade 9 Explanation:
When temperature increases, metal ions vibrate more.
This causes more collisions with electrons.
Therefore resistance increases.
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SERIES CIRCUITS
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Current:
Same everywhere
Voltage:
Shared between components
Resistance:
Added together
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PARALLEL CIRCUITS
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Voltage:
Same across all branches
Current:
Split between branches
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FILAMENT LAMP
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As temperature increases:
- Ions vibrate more
- More collisions occur
- Resistance increases
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TOPIC 3: PARTICLE MODEL OF MATTER
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SOLIDS
Particles:
- Touching
- Fixed positions
- Vibrate only
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LIQUIDS
Particles:
- Close together
- Move past each other
- Random arrangement
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GASES
Particles:
- Far apart
- Move randomly
- High speed
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DENSITY
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Definition:
Mass per unit volume.
Formula:
Density = Mass ÷ Volume
ρ = m ÷ V
Example:
Mass = 600kg
Volume = 2m³
Density = 600 ÷ 2
Density = 300 kg/m³
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CHANGES OF STATE
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Solid → Liquid = Melting
Liquid → Solid = Freezing
Liquid → Gas = Boiling
Gas → Liquid = Condensation
Solid → Gas = Sublimation
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INTERNAL ENERGY
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Plum pudding model.
Rutherford
Gold foil experiment.
Discovered nucleus.
Showed most of atom is empty space.
Bohr
Electrons orbit nucleus in shells.
Chadwick
Discovered neutrons.
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ALPHA RADIATION
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Contains:
2 protons
2 neutrons
Properties:
- Most ionising
- Shortest range
- Stopped by paper
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BETA RADIATION
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Fast electron.
Properties:
- Medium ionising
- Medium penetration
- Stopped by aluminium
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GAMMA RADIATION
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Electromagnetic wave.
Properties:
- Least ionising
- Most penetrating
- Stopped by thick lead
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IONISATION
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Definition:
Ionisation occurs when radiation removes electrons from atoms.
Grade 9 Point:
Alpha radiation is the most ionising because it interacts strongly with atoms and removes electrons easily.
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HALF-LIFE
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Definition:
The time taken for the number of radioactive nuclei to halve.
Example:
800
↓
400
↓
200
↓
100
Each step represents one half-life.
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IRRADIATION VS CONTAMINATION
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IRRADIATION
- Object exposed to radiation
- Does NOT become radioactive
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CONTAMINATION
- Radioactive material transferred
- Object becomes radioactive
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GRADE 9 EXAM SENTENCES
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"Energy is not lost; it is dissipated to the surroundings."
"As temperature increases, ions vibrate more frequently, causing more collisions with electrons and therefore increasing resistance."
"Current is the rate of flow of electric charge."
"Potential difference is the energy transferred per coulomb of charge."
"When a substance is heated, particles gain kinetic energy and move faster."
"Alpha radiation is highly ionising because it removes electrons from atoms easily."