AQA Physics 8463 - Energy Flashcards

Vocabulary flashcards covering AQA Section 4.1 energy topics, equations, required practicals, and energy resources.

System (in physics)

An object or a group of objects being considered.

Energy Transfers in Systems

Energy is transferred between stores or between the system and its surroundings when a system changes.

Conservation of Energy Principle

Energy cannot be created or destroyed; it can only be transferred between stores.

Main GCSE Energy Stores

Kinetic, thermal, gravitational potential, elastic potential, chemical, magnetic, electrostatic and nuclear.

Kinetic Energy Store

The energy store of a moving object.

Thermal Energy Store

Energy associated with the internal energy of an object due to its particles.

Gravitational Potential Energy Store

Energy stored because of an object's position in a gravitational field.

Elastic Potential Energy Store

Energy stored when an elastic object is stretched or compressed.

Chemical Energy Store

Energy stored in chemical substances such as fuels, foods and batteries.

Nuclear Energy Store

Energy stored in atomic nuclei.

Magnetic Energy Store

Energy stored when magnetic objects interact.

Electrostatic Energy Store

Energy stored when electric charges interact.

Main Energy Transfer Pathways

Mechanically, electrically, by heating and by radiation.

Mechanically Transferred Energy

Energy is transferred when a force does work.

Electrically Transferred Energy

Energy is transferred when moving charges do work.

Energy Transferred by Heating

Energy is transferred because of a temperature difference.

Upward Projected Object Energy Change

Its kinetic energy store decreases while its gravitational potential energy store increases.

Moving Object Hitting Obstacle Energy Change

Its kinetic energy store decreases and energy is transferred mainly to thermal stores and sometimes sound.

Object Accelerated by Force Energy Change

Work done by the force increases the object's kinetic energy store.

Vehicle Slowing Down Energy Change

Its kinetic energy store decreases and energy is dissipated mainly to thermal stores of the brakes, tyres, road and surroundings.

Electric Kettle Boiling Water Energy Change

Energy is transferred electrically from the supply to the thermal energy store of the water and kettle.

Kinetic Energy Equation

$$E_k = \frac{1}{2} m v^2$$

Unit of Kinetic Energy

Joule, $J$

Mass Symbol ($m$) in Kinetic Energy

Mass in kilograms, $kg$

Speed Symbol ($v$) in Kinetic Energy

Speed in metres per second, $m/s$

Effect of Doubling Speed on Kinetic Energy

It becomes four times larger because kinetic energy is proportional to $v^2$

Elastic Potential Energy Equation

$E_e = \frac{1}{2} k e^2$, provided the limit of proportionality has not been exceeded.

Spring Constant Symbol ($k$)

Spring constant in newtons per metre, $N/m$

Extension Symbol ($e$)

Extension in metres, $m$

Unit of Elastic Potential Energy

Joule, $J$

Gravitational Potential Energy Equation

$$E_p = m g h$$

Gravitational Field Strength Symbol ($g$)

Gravitational field strength in newtons per kilogram, $N/kg$

Height Change Symbol ($h$)

Change in height in metres, $m$

Unit of Gravitational Potential Energy

Joule, $J$

Effect of Doubling Height on GPE

It doubles, provided mass and $g$ stay constant.

Work Done

Work done is energy transferred by a force.

Joule to Newton-Metre Relationship

$$1\,\text{joule} = 1\,\text{newton-metre}$$

Specific Heat Capacity

The energy required to raise the temperature of $1\,kg$ of a substance by $1\,\text{degree Celsius}$.

Thermal Energy Change Equation

$$\Delta E = m c \Delta \theta$$

Specific Heat Capacity Symbol ($c$)

Specific heat capacity in joules per kilogram per degree Celsius, $J/kg\,^\circ\text{C}$

Temperature Change Symbol ($\Delta \theta$)

Temperature change in degrees Celsius.

Unit of Change in Thermal Energy

Joule, $J$

High Specific Heat Capacity Meaning

A large amount of energy is needed to raise the temperature of the substance.

Required Practical 1 Purpose

To determine the specific heat capacity of one or more materials.

Required Practical 1 Measured Energy Transfer

Electrical work done by a heater is linked to the increase in the material's thermal energy store.

Required Practical 1 Electrical Energy Calculation

Energy transferred = power x time, or from appropriate electrical measurements.

Required Practical 1 Temperature Measurement

The initial and final temperatures, or the temperature change, of the material.

Required Practical 1 Insulation Role

It reduces unwanted energy transfer to the surroundings.

Required Practical 1 Experimental Value Difference

Some energy is transferred to the surroundings or apparatus instead of only heating the sample.

Power

The rate at which energy is transferred or the rate at which work is done.

Power Equation (Energy)

$$P = \frac{E}{t}$$

Power Equation (Work Done)

$$P = \frac{W}{t}$$

Unit of Power

Watt, $W$

One Watt

One joule of energy transferred per second.

Power Comparison of Faster vs Slower Motor

The motor that does the work faster has greater power.

Closed System Total Energy

There is no net change in total energy.

Dissipated Energy

Energy transferred to stores where it is less useful and becomes spread out in the surroundings.

Wasted Energy

Energy no longer usefully transferred for the intended purpose, although it has not been destroyed.

Friction Energy Loss Reduction

By lubrication.

Thermal Energy Loss Reduction

By thermal insulation.

Thermal Conductivity

A property describing how readily energy is transferred through a material by conduction.

High Thermal Conductivity Effect

The rate of energy transfer by conduction is higher.

Wall Thickness Effect on Building Cooling

Increasing wall thickness generally reduces the rate of energy transfer through the wall.

Lower Thermal Conductivity Effect on Cooling

It reduces the rate of energy transfer through the material.

Physics-Only Required Practical 2 Purpose

To investigate the effectiveness of different materials as thermal insulators and factors affecting their insulation properties.

Physics-Only Required Practical 2 Variables

Material type or thickness while keeping other relevant variables controlled.

Physics-Only Required Practical 2 Insulation Measurement

Temperature change over a fixed time, or time taken for a fixed temperature change.

Starting Temperature Control in Insulation Tests

Different starting temperature differences can change the rate of energy transfer.

Efficiency

The proportion of total input energy or power that is usefully transferred.

Efficiency Equation (Energy)

$$\text{Efficiency} = \frac{\text{useful energy output}}{\text{total energy input}}$$

Efficiency Equation (Power)

$$\text{Efficiency} = \frac{\text{useful power output}}{\text{total power input}}$$

Ways to Express Efficiency

As a decimal between $0$ and $1$ or as a percentage between $0\%$ and $100\%$.

Converting Decimal Efficiency to Percentage

Multiply by $100$.

Real Device Efficiency Limit

Cannot be greater than $100\%$ because useful output energy cannot exceed total input energy.

Increasing Energy Transfer Efficiency (HT)

Reduce unwanted energy transfers, for example using lubrication or insulation.

Energy Resource

A source of energy that can be used for purposes such as transport, heating or generating electricity.

Renewable Energy Resource

A resource that is replenished as it is used or can be replenished on a human timescale.

Non-Renewable Energy Resource

A finite resource that is not replenished as quickly as it is used.

Fossil Fuel Energy Resources

Coal, oil and natural gas.

Nuclear Fuel Renewable Status

Non-renewable.

AQA Required Renewable Resources

Biofuel, wind, hydroelectricity, geothermal, tides, solar energy and water waves.

Three Major Uses of Energy Resources

Transport, heating and electricity generation.

Fossil Fuel Reliability

They can provide energy when required and are not dependent on weather conditions.

Wind and Solar Energy Reliability

Their output depends on changing weather and environmental conditions, making them less reliable.

Advantage of Renewable Resources

They are replenished and generally produce little or no greenhouse gas during operation.

Disadvantage of Renewable Resources

Some are intermittent, require suitable locations or have environmental and economic impacts.

Fossil Fuels Climate Impact

Carbon dioxide emissions contribute to climate change.

Fossil Fuels Air Pollutants

Sulfur dioxide, nitrogen oxides and particulates, depending on the fuel and process.

Advantage of Nuclear Fuel

It can provide large amounts of reliable electricity with very low carbon dioxide emissions during operation.

Disadvantages of Nuclear Energy

Radioactive waste, high costs, long construction/decommissioning times and accident risk.

Environmental Impact of Biofuels

Large areas of land may be needed, affecting food production or habitats.

Environmental Impact of Hydroelectric Schemes

Habitats and communities may be flooded or altered.

Environmental Impact of Wind Turbines

Visual/noise impacts and effects on wildlife; output is also weather-dependent.

Environmental Impact of Tidal Schemes

They can alter coastal habitats and ecosystems.

Advantage of Geothermal Energy

It can provide reliable low-carbon energy in suitable locations.

Reasons for Changing Energy Patterns

Technology, cost, availability, environmental concerns, politics and public attitudes change.

Factors in Comparing Energy Resources

Reliability, environmental impact, cost, availability, location and suitability for the intended use.

AQA Requirement for Electricity Generation Details

Not required in this topic; the specification focuses on resources, uses, reliability, environmental impacts and trends.

First Step in Energy Calculations

Identify the correct energy store or transfer and write the relevant equation with units.

Mass Unit Conversion in Energy Equations

Mass must usually be converted to kilograms because standard equations use mass in kilograms ($kg$).