topic 1 Flashcards
What is a system
A single object or a group of objects that you are interested in
What happens when a system changes
Energy is transferred
How can energy be transferred when a system changes
- into or away from the system
- between different objects
- or between different types of energy stores
What are closed systems
Systems where neither matter nor energy can enter or leave
What is the net change in the total energy of a closed system
Always 0
4 ways energy can be transferred
- mechanically
- electrically
- by heating
- by radiation
What is work done
Energy transferred
How can work be done
When current flows or by a force moving an object
When is energy transferred to the kinetic energy store?
When an object speeds up and is transferred away from the store when an object slows down
What does the energy in the kinetic energy store depend on?
The objects mass and speed
The greater its mass and the faster its going … (kinetic energy)
The more energy they will be in its kinetic energy store
What does lifting an object in a gravitational field require?
Work
the higher the object is lifted … (GPE)
the more energy is transferred to this store
what does the amount of energy in a GPE store depend on
the object’s mass, its height and the strength of the gravitational field the object is in
what happens to energy when an object falls
energy from its gpe store is transferred to its kinetic energy store
energy lost from the gpe store =
energy gained in the kinetic energy store
how can you transfer energy to an objects elastic potential energy store
by stretching or squashing an object
what is specific heat capacity
the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree
how much joules do you need to warm 1kg of water by 1 degree
4200 j
what is the conservation of energy principle
that energy can be transferred usefully, stored or dissipated but can never be destroyed or created
what is dissipated energy
wasted energy
what is power
the rate of energy transfer or the rate of doing work
what are lubricants used to do
reduce the friction between the objects surfaces when they move
what are lubricants usually in the form of
liquids
why are lubricants usually liquids
so they can flow easily between objects and coat them
what is thermal conductivity
a measure of how quickly energy is transferred through a material
how are useful devices useful
because they can transfer energy from one store to another
usually what store is wasted energy transferred to
thermal energy store
what is a more efficient device
one which less energy is wasted
how can you improve the the efficiency of energy transfers
by insulating objects, lubricating them or making them more streamlined
what are the 3 main fossil fuels
coal, oil and gas
2 examples of non-renewable resources
fossil fuels and nuclear fuel
2 reasons why fossil fuels are bad
- will run out one day
- damage the environment
why are fossil fuels good
-they provide most of our energy
7 renewable energy sources
SWWHBTG
- sun
- wind
- water waves
- hydro-electricity
- bio-fuel
- tides
- geothermal
