Energy Flashcards
what’s the law of conservation of energy
energy cannot be created or destroyed
only transferred from one store to another
what are examples of energy stores
thermal
kinetic
magnetic
gravitational potential
elastic
electrostatic
chemical
what’s the equation for kinetic energy
1/2 mass x velocity ^2
what’s the equation for gravitational potential energy
mass x gfs x height
equation for elastic energy
1/2 spring constant x extension ^2
what’s a system
an object or group of objects
what happens when system changes
energy is transferred
what’s internal energy
total energy stored by the particles making up a system or substance
what does internal energy consist of
potential energy stores
kinetic energy atores
what’s specific heat capacity
the amount of energy needed to raise the temperature of 1Kg of a substance by 1•C
what’s the equation for specific heat capacity
energy= mass x SHC x change in temp
where is energy lost
in surroundings
what is power
the rate at which energy is transferred
OR THHE RATE AT WHCIH WORK IS DONE
what’s the equation for power
power= energy/ time
OR
power= work done/time
how does lubrication prevent energy loss
oil in a motor e.g
reduces friction by making the object soft and slippery
therefor less energy is lost (heat)
how does thermal insulation prevent heat loss
thick walls
double glazed windows
reduces conduction
The higher the thermal conductivity…..
the more easier that heat is allowed to travel through material
what are energy sources used for
transport
electricity generation
heating
what are the advantages and disadvantages of renewable energy
bad- not the most reliable e.g solar dosent work in bad weather
bad- cannot provide large amounts of energy so easily
good- can be replenished as it’s used
what are some examples of renewable energy
biofuel
wind
solar
what are disadvantages of non renewable
produces more waste
releases harmful emissions
what is an advantage of non renewable energy
can produce large amounts
what are some examples of non renewable energy
fossil fuels
nuclear fuels
what are some ways to transfer energy stores
mechanically- e.g physically pulling on an elastic band
Electrically- e.g plugging in a lamp
Heating
Or by radiation - light or sound waves
What happens when energy is transferred in a open system
it can exchange energy with the outside and can lose or gain energy from surroundings
what happens when energy is in closed system
no matter or energy can enter the system
so overall change is 0
what’s an example of transferring energy
plugging in a kettle
Electrical energy is transferred electrically to the thermal energy into the kettle and therefore into water
what is mechanical work done
the force used to move an object
what is electrical work done -
When current flows and energy is required to overcome the resistance in wires
what happens when particles are heated
tranfers energy to kinetic energy store through heating
what does temperature mean
average internal energy in a substance
How do you turn Kj into J
X 1000
how do you turn g into kg
divide by 1000
how do you avoid losing heat energy to surroundings
insulate it
use a lid for a closed container
when is work done used
when force is used to move an object
what’s the diffrence bettween energy transferred and work done
energy transferred does not require force or movement
what is time measured in
Seconds
what are some ways to reduce unwanted energy transfers (e.g heat loss)
Thermal insulation
Lubrication
What are some ways to reduce convection ( heat transferred by liquid or gas)
Seal closed on house so air isn’t able to escape
Insulating foam inside cavity walls
What are some ways to reduce conduction( heat transfer through as solid)
Thick walls
Two layers of brick (cavity walls)
double glazed windows
how does lubricatjng objects reduce friction
makes it soft and slippery
so less force/ work done has to be done
What’s the disadvantage of friction
Reduces efficiency
Heats up
what is energy mostly used for
transport (oil for cars)
domestic uses e.g cooking and heating
