energy transfer and electricity revision Flashcards
(30 cards)
what is the unit of energy?
Joule (J)
what are the 8 stores of energy ?
- thermal
- kinetic
- Gravitational potential
- elastic potential
- chemical
- magnetic
- electrostatic
- nucleur
what is meant by an energy transfer?
An energy transfer is when energy moves from one store to the other or from one object to another
Describe the energy transfers when a ball is thrown into the air
- Kinetic energy is transferred into gravitational potential energy as it rises
- As it falls, gravitational potential is transferred back into kinetic energy
what is the law of conservation of energy?
the law of conversion of energy states that energy cannot be created or destroyed, only transferred or stored
Give an example of energy being dissipated
when a light bulb is on some energy is dissipated as heat to the surroundings
what is meant by useful energy?
Useful energy is the energy transferred to where it’s wanted, in the form that’s wanted
Equation for kinetic energy:
KE = ½ × mass × speed²
calculate the kinetic energy of a 2kg object moving 3 m/s
KE = ½ × 2 kg × (3 m/s)² = ½ × 2 × 9 = 9 J
state the equation for gravitational potential energy
GPE = mass x gravitational field strength x height
calculate the GPE of a 1.5kg object raised 2m above the ground
GPE = 1.5kg x 10N/kg x 2m = 30 J
what is the equation for elastic potential energy
EPE = ½ × spring constant × extension²
Describe how electricity is generated in a coal- fired power station
- coal is burned to heat water
- this produces steam whch turns a turbine
- the turbine drives a generator to produce electricity
How does a gas- fired power station differ from a nuclear power station in the way it produces energy?
A gas- fired station burns gas directly to heat water into steam. A nuclear power station uses nuclear reactions to produce heat for steam
what is the energy source for a hydrielectric power station?
the energy source for a hydroelectric power station is gravitational potential energy of stored water
Explain how wind turbines generate electricity
Wind turbines use wind to turn blades, which spin a turbine connected to a geenerator that produces electricity
how is electricity generated using solar panels?
solar anels (photovoltiac cells) convert sunlight directly into electricity
what is geothermal energy and how can it be used to generate electricity?
Geothermal energy is heat from inside the earth. It can heat water into steam to turn turbines and generate electricity
what are the advantages of using fossil fuels for electricity generation?
- reliable and consistent
- high energy output
- Infastructure already exists
what are the disadvantages of using fossil fuels?
- produce greenhouse gases
- non- renewable and will eventually run out
Give an environmental impact of burning coal for energy
Burning coal releases carbon dioxide, which contributes to global warming
what are the benefits of nuclear power?
- produces a lot of energy from a small amount of fuel
- no greenhouse gases released during operation
what are the disadvantages of nuclear power?
- produces radioactive waste
- expensive and takes a long time to build
what are the advantages of solar energy?
- renewable
- no pollution or greenhouse gases
