Topic 2 - energy THERMAL PHYSICS Flashcards
What is chemical energy strore ?
Incldues fuels , foods or chemicals found in bateries .
What is kinetic energys troes ?
includes energy of object because it is movign .
What is gravtiational potenitaly energy?
Describes energys tores of an object because of its position , such as an object above the ground .
What is elastic potential nergy ?
energy store in an object when it is streched or swaushed
What is elastic potential energy ?
Used to desrvive energy in a springy object when you strech or squash it .
What is thermal energys tore ?
Describes energy of a substance due to its temp ..
enertransfers in a torch lamp .
Chemcial energys tores in batter —> electric current in wired –> energy transgferrred to surroudnigns as light waves + thermal energys tore of surroudnigns ..
object falling
gpe —> kinetic energy store –> energ of surroundings —> thermal energys tore of surroudnigns and sound waves .
Four ways energy can be transferred .,
Mechanically - By the action of a force.
Electrically - By an electrical current.
By radiation - By Light waves or Sound waves.
By heating - By conduction, convection or radiation.
What is the law of conservation of energy ?
Enrgy can br transferred usuefullys tored or disspiated but cannot be created or destroyed .
How does a Sankey Diagram work?
Width energy tranansferred 60J
Straigh arrow is useful energy J
bent arrow bdown is wasted energy 20J
What is efficency ?
Efficency is a measure of hwo good a device is at ransferrign energy usually from one store to anothe r.
-More efficent a device is , less energywasted
-all devices waste energy so no device hudnred rpecent efficent .
Equation for efficeincy ?
Useful output energy / total input energy
times by 100 for percent
NO efficency should be greater than 1 or you have done it wrong .
how to imporve efficency
dfriction between moving parts cause heating - lubricae moving parts to reduce frction .
Resistance of wire causes wire to get hot when curent passes throurgh - use wires wilth litle elctrical ressitance ,
air resitance on object ooposting motio - stremamline obect to reduce air resistance ,
sound caused by machinery - tighten loose parts reducing vibratio cutting out nosie .
first stage of thermal insualtors rqp ?
Compare effectiveness of different mterials as insulators aim .
-place small beaker isnide a large beaker
-boil water ,a dd 10cm cubed of hot water into smal beaker .
second stage of thermal insualtors rqp ?
Use a piece of cardobard as lid for beaker .
-have a hole in lid for thermometer , Place thermometer i hot warer , maing sure bulb of thermomeer is in hot water .
third stage of thermal insualtors rqp ?
independant - maetiral
control-volume of water , mass of material
-dependedan - temp of wate r.
Recall starting temp of ater and star tropwach record temp for 3 min for every 15min
repeat experiment with different insualting materials (but betwen small and big beaker) . like bubble wrap and fabric .
What are results of the rqp ?
-Coolin g curves
-msot effective isnulitng mterial , water will cool down most slowly with msot effetcing isnulating material (last line ).
inevsiage thickness of material .
-repeat experiemnt ut this time using on emaateiral whic is our control as well as sgtart temp
indepenant changin layers (do 2 , 4 y layers)
-more layers of material , mroe slowly water cools , Most effective thermal insulator than fewer layers .
The higher the thermal conductivity of a material …
The higher the rate of energy transfer by conduction across that material .
One type of insualtion in houses ?
-between brick wall and breeze wall has a caviity - howeert his has a high thermal condcutivity
-so builders put INSULATING MATERIAL between the walls which have a low rhermal conductivity .
-Double glazed windowns also have low thermal conducivity - less energy leavs the house interiori .
Another type of insualtion in hosues ?
Loft insultio - low thermal conductivity, reducing rate at which thermal neergy passes thorugh .
-Reduce thermal enrgy transfer forma hosue by using materials with low themral conducitivity ,
Thick walls also reduce rate of thermal energy transfe r.
What is a renewable energy source ?
A renewale enegry source is one that is being repelnsihed or can be replenised as it is used .
examples of reenwable resources ?
-Wind
Solar
Hydro
Biofuels
Geothermal
.Nuclear
Nuclear pwoer
-Used to generate electricity but doesn’t bburn so dont realse greenohsue gases.
–extremley reliable a lot of electricity
-but radioactive waste must be stored for many eyas until it safe to be processed very dangerous for environemnt .
-decomissionign power station mny years , expensive .
Bio fuels ?
-Produced from burning plants to produce steam.
-Carbon neutral as it dosen’t add to global warmming , renwable plants gorwn produciing more biomass ,
HOwveer if we use land for growing fuels for crops , could push up price of food
Solar Power
Transfer energy from sun by eelctic current ,
-Expensive but good in places that sunny .
unreliable in uk not lawyas sunny .
Hydroelectirc power
-dams are built form large reservoirs .
gates can be opeoened to let water in as it does turns turbines and egenerates electricity
can destroy habitats when dams are built .
Tidal Power
Relies on seawater building up behind barrer at high tide .
GaaRS WITHIN BARRIER OPEN TO ALLOW WATER IN
HOWEVER THIS CAN DESTROY HABITTS ANFD EXPEENSIVE
Wave power
Air is trapped between waves and atrubine , as waves rises and falls it puhses air through turbine .
What do nuclear power stations run on ?
NOn renewable
Run oon elemnts uranium and Plutonium
Give the three fossil fuels .
-Coal
-Oil
-Natural gas
Advantages of fossil fuels .
-reliable , always provide enrgy when we need it .
-release a great deal of energy- aeroplanes ,
-quiet abundant so relativel cheap
-extremly versatile .
Disadvanagtges of fossil fuels ?
-Releases a huge amount of Co2 contributes to climate change .
-non renewbal ecanotbe repleished as we use so will run out
-also relases pollutnts like carbon particles and nitrous oxide which is harmful to environemnt .
How does power station work ?
-fossil fuels is burned and heats water in boiler .
-Biling water becoes steam and steam turns the turbine .
-The turbine turns the generator and electriciy is produced .
-low pressure steam is condendsed bck into water in cooling towers and water is resued .
