CP3- Conservation Of Energy Flashcards
name the 8 energy stores.
- kinetic- moving
- thermal- heat
- chemical- things that can release energy by a chemical reaction
- gravitational potential- in a gravitational field and can fall
- elastic potential- stretched
- electrostatic- two charges that attract or repel
- magnetic- two magnets that attract or repel
- nuclear- energy stores inside atoms
what is kinetic energy?
- energy stored in moving objects
- the amount of kinetic energy stored in a moving object depends on mass and speed
what is the equation for kinetic energy?
kinetic energy= 1/2 x mass x speed^2
what is gravitational potential energy?
- energy that is stored due to an object being at a height above the earths surface
- the amount of GPE depends on the mass, the strength of gravity and the distance above surface
how do you calculate GPE?
GPE= mass x gravitational field strength x change in vertical height
what is the law of conservation of energy?
energy cannot be created nor destroyed, it can only be transferred from one store to another. this involves useful energy aswell as wasted energy
what is efficiency?
the amount of energy that is transferred, not involving wasted energy
what does dissipated mean?
transferred to surroundings
how can you reduce friction to reduce wasted energy by heating
substances that can lubricate like oil or gases
describe an example of energy transfers on a motor lifting a load.
- energy is transferred electrically from the main
- kinetic energy from the motor is transferred to the kinetic energy and GPE stores of the load
- some of the wasted energy includes the energy transferred mechanically to the thermal energy stores, generating heat
- also the energy transferred electrically to the thermal energy of the circuits
how do you calculate efficiency?
useful energy transferred by device / total energy supplied to device
how does lubrication reduce wasted energy?
- reduces energy transferred by friction, reducing the amount of energy in the thermal store and therefore reducing how much heat is dissipated
how does insulation reduce wasted energy?
- reduces the amount of energy transferred by heating
- reduces conduction so energy transfers slower across materials and can be preserved
how is energy transferred by heating in conductors?
- vibrations are passed between particles in a solid
- metals are good conductors
what is thermal conductivity?
how well a material transfers energy by when heated
how is energy transferred by heating in convection?
fluids that are warm rise and create a convection currents
how do you decrease the rate of energy transfer by heating in a material?
- increase thickness
- decrease thermal conductivity
what are non renewable energy resources?
- will run out one day
- fossil fuels and nuclear fuels
positive of non renewable energy.
- reliable since there is still a lot for current demand
- low costs to build and run fossil fuel
negatives of non renewable energy.
- nuclear power plants are costly and difficult to safely decommission
- fossil fuels are running out
- co2 emissions enhance the greenhouse effect, contributing to global warming
- coal and oil burning can release sulphur dioxide causing acid rain
- oil spillages can damage the environment
- nuclear waste is very difficult to dispose of
what are renewable energy resources?
- will never run out
- biofuels, hydroelectric power, wind power, solar power, tides
positives of renewable energy.
- do not cause pollution or emit carbon dioxide
negatives of renewable energy.
- cannot be the primary resource since its not always available
- don’t provide enough energy
- getting them to operate in the first place may need to utilise fossil fuels and non renewable power sources so it is counterproductive
what are biofuels?
- renewable energy created from animals waste or plants
- they are carbon neutral since they emit the same amount of carbon they absorbed from the atmostphere
- however energy will be needed to grow and harvest the crops so its not fully carbon neutral
