GCSE physics Topic 3 - Conservation of energy

What is a Sankey diagram ?

a Sankey diagram shows the amount of energy transferred . the width of the arrows represents the amount of energy in joules

What is the equation for Kinetic energy ?

mass - Kg Velocity - m/s^2

What are some ways that we can reduce energy transfer ?

- Between two moving parts you could add lubricant so that friction is reduced - Making sure all the fuel going into an engine is burned - or finding ways of using the energy transferred by heating that would otherwise be wasted

Analyse the changes involved in the way energy is stored when a system changes : When a vehicle slows down

- Energy stored in the moving car , kinetic energy - the energy is transfered by forces during braking to heat energy stored in the breaks , thermal energy ,

Describe the main energy sources found in the earth : Tidal power

- It can be generate electricity when turbines in a huge barrage (dam) across a a riverestuary turn as the ides flow in and out - Tidal power is not available all the time however it is available at predictable times - There are not many places for this in the uk because it could harm widlife and sea animals

Describe the main energy sources found in the earth : Hydro-electricity

- It is generated by falling water in places where water can be trapped in high reservoirs - It is available at any time (as long as the reservoirs don't dry up ) - A hydroelectric power station can be started and stopped very quickly unlike fossil fuel power stations

Describe the main energy sources found in the earth : Wind

- Wind turbines can be used to generate electricity as long as the wind speed is not too slow or too fast - A lot of wind turbines are needed to produce the same amount of energy as fossil fuel-fuelled power stations and some people think they ruin the landscape

Analyse the changes involved in the way energy is stored when a system changes : - Bringing water to boil in a electric kettle

- energy transfered to the kettle by electricity ends up as a store of thermal energy in the hot water - As the hot water is at a higher temperature to the kettle and the surroundings some energy is transfered to these things by heating. - Energy can also be transfered by light and sound

Describe the main energy sources found in the earth : nuclear fuels

- nuclear fuels such as uranium store a lot of energy in a small piece of material. - this make nuclear fuels very useful for spacecrafts , where the mass of fuels is important - Nuclear power stations do not emit any carbon dioxide or other gasses - However the waste products are radioactive for millions of years This is expensive to dispose of safely -It is also very expensive to decommission (dismantle safely ) a nuclear power station at the end of its life - a lot more than fossil-fueled power station -

Describe the main energy sources found in the earth : Fossil fuels

- such as coal , oil and natural gas - Its a non renewable whcih means it will run out one day - Petrol and diseal are fossile fuels made from oil -They are used in vehicles aeroplanes and ships becasue they store alot of energy and they are easy to store and to use in engines - Natural gas is used for cooking and heating homes - Buring fossile fuels releases carbon dioxide and other gasses.They contribute to climate change.Other emmisission from vehicles cause further pollution -Buring natural gas causes less pollution than burning coal. Natural gas power stations also emit less carbon dioxide than other fossil-fueled power stations producing the same amount of energy

Describe the main energy sources found in the earth : Bio- fules

-They can be used in the same way as fissile fuels -They are made from animal wastes or plants -Bio fuels can be made from wastes of wood or from parts of plants that are not used for food , however some crops are grown specifically to be made into bio-fuels. - they are called CARBON NEUTRAL because when they burn they release the same amount of carbon dioxide that they they took from the atmosphere to grow -However energy is needed to grow and harvest the crops and to turn them into fuel , so most bio-fuels are not really carbon neutral

What is the energy store name of these types of energy ? : energy stored in atoms

Atomic energy or nuclear energy

What is the calculation for change in GPE ?

Change in GPE (J) = Mass (Kg ) x Gravitational strength (N/Kg) x change in vertical height (m)

Describe the effect does this factor have on thermal insulation ? : Thermal conductivity

Decreasing themral energy will decrease the energy transfer - bad themal conductor = good insulator

What is meant by conservation of energy ? relating it to the law of conservation and what is energy measured in ?

Energy cannot be created or destroyed , it can only be transferred from one store to another .This is called the law of conservation .This means that the total energy transfered by the system is the same as the energy put into it , in JOULES .Although energy is conserved it is not always transfered into forms that are useful.

What is the energy store name of these types of energy ? : energy stored in high positions

Gravitational potential energy

What happens to energy in a closed system ?

In a closed system where there are energy transfers there is no net change to the total energy in that system

What happens to the energy that is dissipated from systems ?

In all systems , changing energy causes dissipation and so the energy is stored in less useful ways For example in a light the electrical energy is transferred by heating , a less useful store of that energy

What is a system ?

It describes something in which we can study changes

Explain how efficiency can be increased ?

Making sure that as much of the energy put into the device is used as possible - use lubricants so friction is reduced -finding ways of making sure all the fuel is being used - re-purposing the energy transferred by heat

What is the equation for the change in gravitational potential energy?

Mass - Kg GFS - N/Kg change in veticle height - m

What happens when machines heat ?

Mechanical processes become wasteful when they cause a rise in temperature so dissipating energy in heating the surroundings

Describe the main energy sources found in the earth : Solar cells

Solar cells convert solar energy directly into electrical energy , in solar farms or on house roof-tops - Solar energy can also be used in power stations -Solar energy can be used to heat water for use in homes - It is not available at all times

Analyse the changes involved in the way energy is stored when a system changes and what factors effect this : When something is moved upwards ?

The further something is moved up the greater the store of GPE - However the amount depends on the mass and the strength of the gravity and how far an object is moved upwards

Describe the effect does this factor have on thermal insulation ? : the temperature difference

The lower the temperature difference the less heat that is going to escape - Small temp difference= less energy will be transfered

What is the energy store name of these types of energy ? : energy stored in hot objects

Thermal energy

What is the energy store name of these types of energy ? : energy stored in food , fuel and batteries

chemical energy

What is the energy store name of these types of energy ? : energy stored in moving objects

kinetic energy

What are the energy store names of these types of energy ? : -Plural energy stored in streched squashed or twisted materials

strain energy or elastic potential energy

Describe the effect does this factor have on thermal insulation ? : thickness of walls

the thicker the wall the more energy is going to be kept in - thick = good insulator

what is the equation for efficiency

useful energy supplied by the device / total energy supplied to the device