P1 Energy (paper 1) Flashcards
What is energy transferred between
energy stores of the object
What are the energy stores
Kinetic
Electrostatic
Thermal
Magnetic
Chemical
Nuclear
Elastic
Gravitational
(Naomi Campbell Met Grace Kelly To Eat Enchiladas)
What’s are the different ways energy is transferred between stores
mechanically
electrically
by heating
by radiation
What is the conservation of every principle
Energy can be transferred usefully, stored or dissipated, but never be created or destroyed
What is a system
a system is a collection of objects/bodies in which energy gets transferred between
How is energy transferred in a system
into/away from the system between different objects in the system/different energy stores
What are closed systems
systems where neither matter nor energy can enter or leave
What is the total energy of a closed system
always zero
what is work done
The amount of energy transferred
What needs to happen for work to be done
current flowing
If a ball was dropped, then what force does the work
gravitational force
What is the unit of work done
Joules (J)
When is energy transferred to a kinetic energy store
when an object speeds up
when is energy transferred away from a kinetic energy store
when an object slows down
What does the energy in the kinetic energy store depend on
the objects mass and speed
If the mass and speed of an object is high, then what will the kinetic energy store be like
there will be more energy than a lighter, slower object
what is gravitational potential
energy stored by objects that are lifted above the ground
What do you need to lift an object in a gravitational field
work
How do you increase the gravitational potential
Raise the object higher
What affects the amount of energy in a GPE store
the objects mass, its height and the strength of the gravitational field the object is in
What happens in the energy stores when an object falls
energy from its gravitational potential energy store transfers to its kinetic energy store
What does air resistance do to some of the energy
Air resistance creased friction leading to some energy being transferred thermally
What is elastic potential energy
energy in a stretched or squashed object
What happens to some of the energy when it gets transferred
Some of the energy dissipates into the surroundings when an energy transfer takes place
What is dissipated energy
energy that has not transferred usefully is has been wasteful
What is power
power is the rate of energy transfer
what is the unit for power
Watts (W)
What does Watts mean
how many joules transferred per second
How could you describe a ‘powerful machine’
a machine that transfers a lot of energy in a short space of time
How do you increase the power of an object
Increase how much energy is being transferred and reduce how long it takes for it to be transferred
How do you reduce wasted energy
adding lubrication to prevent friction and adding thermal insulation to prevent thermal energy also caused by friction
What does Lubrication do
reduce frictional forces
Why are lubricants normally liquid
so that they can flow easily between objects and coat them
What is an example of a lubricant
oil
What does insulation do
reduce the rate of energy transfer by heating
How can you prevent energy losses through heating in a home
have thicker walls that are made from a material with a low thermal conductivity
Use thermal insulation (double glazed windows, loft insulation)
What do most energy transfers involve
waste energy
Why are useful devices useful
because they can transfer from one store to another
What is efficiency
the measure of how much input energy of a system in transferred usefully
What affects efficiency
the amount of input energy wasted
How can you improve the efficiency of an energy transfer
insulating, lubricating or making the objects more streamlined
How do you write efficiency
As a decimal or a percentage
What doesn’t efficiency have a unit
because it is written as a percentage or decimal of how much energy is usefully transferred
What is the maximum percentage of efficiency
100%
