energy Flashcards
(26 cards)
how much energy is stored in food?
different foods store different amounts of energy
how much energy is stored in food?
different foods store different amounts of energy
recall the different food groups. which stores the most energy?
protein. fats. dairy. carbs. fruit + veg. minerals. vitamins. fats and oils store the most energy
what do food labels tell us?
how much energy is stored in food
what is an energy store
something, such as food or hot objects, that holds energy. cannot be destroyed/created, but transferred
what does the law of energy state
energy cannot br created or destroyed, it can only br moved from one store to another
equation for efficiency
useful energy output/total energy input
what is thermal energy
the energy contained within a system that is responsible for its temperature.
what is equilibrium in energy
when objects r at the same temp, they are at thermal equilibrium
what is thermal energy
a kind of energy which is generated when the temp rises. it is directly proportional to the change in temp of the object
what happens when u heat things up
the particles form kinetic energy
what happens 2 particles when an object turns from solid to liquid
particles gain thermal energy which allows them to partly overcome the strong forces holding them in place. the particles begin to move from their fixed positions but are still closely spaced together. the substance has melted to become a liquid
dull, matt or rough dark coloured surfaces have
good absorption and emission
shiny light coloured surfaces have…
poor absorption and emission
waffle abt infrared radiation.
all objects emit infrared radiation. although we cannot see it we feel it as heat. conduction and convection both need particles to transfer energy. radiation doesn’t. thr type if radiation emitted depends on the temp of the object, whilst the amount of radiation emitted depenes on the tyoe of surface.
how can infrared radiation be detected.
by our skin. using a thermal imaging camera or a remote thermometer.
infrared radiation can be
transmitted :
any object that has a temp radiates infrared.
absorbed:
infrared light has frequencies which r absorbed by chemical bonds. the internal energy of the bonds increases when they absorb infrared light, which causes heating.
reflected:
all objects emit and absorb infrared radiations. they do this whatever their temp is. the hotter the object, the more infrared radiation, the greater the proportion if emitter radiation is visible light.
which colours absorb infrared radiation better
dark colours
what r fossil fuels
non renewable sources of energy
disadvantages of using fossil fuels
acid rain. deforestation. air pollution. global warming.
how is coal formed
a slow process called coalification. stagnant water, like in swamps lacks oxygen which allowe plants 2 be preserved. the higher the rank of coal, the higher the carbon content and the shinier it appears
what r fuel + oil
fuel - a substance that is burned or otherwise used 2 produce heat or energy.
oil is primarily composed of hydrogen and carbon
what does burning of fossil fuels do
produces acidic gases like sulphur dioxide which causes acid rain. produces large amounts of carbon dioxide which goes into the air. this causes an increased greenhouse effect which leads to the earth getting warmer.
how does solar energy work
by capturing sunlight which gets converted into electricity. it is abundant and widely available. disadvantages - daylight dependent. expensive.
