P1,2&3 energy Flashcards
what is a system
an object or group of objects
what happens when a system changes
there are changes in the way that energy is stored
what is internal energy
the total kinetic and potential energy
what is the conservation of energy
energy cannot be created or destroyed
how do you reduce unwanted energy transfers
lubrication
thermal insulation
what is meant by thermal conductivity
how well a material conducts energy when heated
what are the two walls of a house called
external brick wall
internal breezeblock wall
what keeps houses warm
insulating material which a a very low thermal conductivity and reduces overall thermal conductivity of the wall by over 10x
why do houses have double glazed windows
they have a very low thermal conductivity so less heat escapes
what is loft insulation
a material with a low thermal conductivity so less thermal energy passes through
what is the equation for power
power = energy / time
why can no device be more than 100% efficient
you cant get more energy than you put in
how would you investigate the heat capacity of materials
measure start temperature
switch on electric heater
measure end temperature
measure voltage and current to find power
repeat using different liquids
calculate specific heat capacity
what is the specific heat capacity
the amount of energy required to raise the temperature of one kilogram of the substance by 1 degree Celsius
what are earths main energy resources
fossil fuels (coal, oil and gas),
nuclear fuel,
bio-fuel,
wind,
hydroelectricity,
geothermal, the tides,
the Sun and water waves
what is a renewable energy source
an energy source which can be replenished
what is a non renewable energy source
energy sources which will eventually run out
what are the uses of energy resources
heating
transport
electricity generation
what happens in a closed system
total energy never changes but it can be transferred from one store to another
what are the energy transfers when an object is projected upwards
kinetic energy to gravitational potential
what are the energy transfers when an object hits an obstacle
kinetic energy to thermal and sound energy
what are the energy transfers when a car is accelerating
chemical to kinetic
what are the energy transfers when a car brakes
kinetic to thermal
what are the energy transfers when water boils in a kettle
electrical to thermal
