P1 Flashcards
Name 5 energy stores
Thermal energy stores Chemical energy stores Kinetic eneregy stores Elastic energy stores Gravitational potentiol energy stores
What is chemical energy
This stores fuels,foods and the chemical found in batteries
What is kinetic energy
Describes the enrgy an object has because it is moving
Gravitational potential energy store
Describes the energy an object has becuase of its position relative to the ground
Elastic pontential energy
Describes the energy an object has because it is being stretched or squashed
Thermal energy strore
Describes the energy an object has because of its temperature
How can energy be transfered
Heating,waves,an eletric current, or when a force moves an object
What does conservation of energy mean
Energy cannot be created or destroyed
What is a closed system
An isolated system in which no energy is transfers take place out of or into the enrgy store of a system
When is work done on an object
When a force is used on the object
Energy transfered=
Work done
What happens when no force is being used on an object?
No work is being used or done
What happens when the gravitational enrrgy of on abject move down
The energy is decreasing
What do all moving objects have?
Kinetic energy
How can the object have more kinetic energy?
The greater the mas and the greater the speed of an object
What is the kinetic energy store of an objec?
Ek= 1/2 m v2
Where is the elastic potnetial enrgy stored?
An elastic object that has been squashesor stretched
What is the elastic potential energy in a stretched spring?
Ee=1/2 k e2
What is useful energy
Energy in the place we want it
What is wasted energy
Energy that is not useful and is transfered by an undesired path way
What eventually happens to wasteful energy?
It is transfered to the surroundings,which becomes warmer
The efficinecy of a device=
Useful energy transfered by the device\divided\total energy supplied to the device
Why do machines waste energy?
Due to friction. Between their moving parts,air resistance and noise
How can machines be made more effiencient?
Reducing the energy they waste
What supplied most in a home?
electricity,gas and oil
Why is an eletrical appliance designed in a particular way
Reduce waste
What is the equasion of an appliance?
P=E/t
What is the equasion of the effiency of an appliance?
Usefulpowerout\divided by\ total power in(x100)
What is the equasion of the power wasted by an appliance
Total power input - useful power output
