Autmun Topic Test Flashcards
What is a system
Group of objects
When a system changes the way the energy is stored
Changes
Energy can be transferred usefully, stored or dissipated,
Bu cannot be created or destroyed
Work done is measured in
J joules
Force is measured in
N newtons
Distance os measured in
M metres
1 joule =
1 newton metre
Work done against a frictional force causes
A temp rise of the object
Gravitational potential energy
Ep in joules
Mass is measured
In kg
Gravitational field strength
G is in newtons per kg
Height
In metres
Kinetic enrgy
Ek in joules
Ways of reducing unwanted energy transfers
Double glazed windows to stop thermal enrgy transferring ,lubrication to reduce friction and therefore heat energy transfer
Ways to increase the efficiency of an intended energy transfer
Reduce the amount of enrgy transferred to thermal so heat that is unwanted again by lubrication or insulation
1 joule per second is
1 watt
Power
P in watts W
Energy transferred
E in joules J
Time
T in seconds S
Work done
W in joules
Two motors lift the same weight to the same height but one does it quicker
Rate if change of energy so in this case the transfer if enrergy is work done to kinetic . So as one is more powerful it makes one rate of change quicker than the other
Main enrgy sources on earth
fossil fuels (coal, oil and gas), nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, the tides, the Sun and water waves
Renewable energy source
One that is being replenished as it is being used
Uses of energy resources :
Transport, electricity generation,and heating
