Topic 1- Energy Flashcards
Define specific heat capacity of a substance
the amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 celsius
What is the definition for power
the rate at which energy is transferred
Describe the energy changes when a ball is thrown upwards
- upwards- chemical energy in the muscles convert to ke converted to gpe
- peak- maximum gpe, zero ke
- downwards- gpe is converted to ke
Describe energy changes for a bunjee jumper
- falling- gpe converte to ke
- as cord tightens , ke is converted and stored as gpe
- lowest point- jumpers initial gpe equals elastic potential energy stored in rope.
examples of chemical energy stores
- food
- fuel
- batteries
State the law of energy conservation
energy cannot be created or destroyed, only transferred into different forms
State any changes in the total energy of a ball that is kicked, assuming that no external forces act.
the total energy of the system remains constant due to the conservation of energy
What is waste energy?
energy that is not used by the device for its desire purpose
Describe the energy changes that occur in a filament light-bulb
- electric energy is transferred into light and heat energy
- light is a useful energy form, heat is wasted
How can the efficiency of a system be increased?-
- reducing waste output (lubrication, thermal insulation)
- recycling waste output (recycling thermal output energy as input energy)
state the consequences for energy transfer of a material with a high thermal conductivity.
the rate of energy transferred through the material is higher than for the material with a lower thermal conductivity
do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows?
lower, meaning less energy transfers through them
what factors affect the rate of cooling for a building?
- thickness of walls
- thermal conductivity of walls
methods of reducing heat loss in a building
- double glazing
- loft and wall insulation
- thicker walls
What is a renewable energy source?
an energy source which can be replenished as its used up
4 examples of renewable energy sources
- wind
- hydro
- solar
- tidal
advantages of using gas instead of coal
- flexible generation: gas power stations have short start-up times so it can be switched on and off more readily
- lower emmissions of co2
disadvantages of using renewable energy resources
- output controlled by external factors so supply uncertain
- more economic and efficient benefit using non-renewable
advantages of fossil fuels
- reliable
- cost effective
- large amount of energy produced
advantages of nuclear power
- very large amounts of energy for relatively small amounts of fuel
- doesnts release greenhouse gases
- low fuel costs
disadvantages of nuclear power
- produces nuclear waste harming humans and must be stored safely
- non-renewable
- risk of nuclear accidents fatal for humans and envionments
how does hydroelectic power produce energy?
- rainwater collects behind a dam
- when this water is released, it is used to turn a turbine
- turbine turns a generator which produces electricity
disadvantages of using biofuels
- plants burned or decay, release co2
- in order to grow biofuels, need to destroy land
- growing biofuels reduces land for crops
advantages of using tidal energy
- no greenhouse gases produced
- reliable as tides happen twice a day
- cheap as tides are natural
