7H Energy Flashcards
What is the conservation of energy?
Energy cannot be created or destroyed, only transferred from one store to another
Name the types of energy store shown in the 3 pictures.
Thermal, gravitational potential, kinetic, chemical, electrical
What energy store fills up when a spring is stretched?
Elastic potential
What energy store empties as a skydiver falls?
Gravitational potential
State the four ways energy can be transferred.
Heating, mechanical, radiation, electrically
True or false? “Heat moves from cold places to hot places.”
False – heat energy is transferred from hot places to cold
How is all energy eventually stored?
Thermal
What is meant by “wasted energy”?
Energy which spreads out and transferred to less useful stores
What does the term dissipate mean?
Spread out
In what store is most dissipated energy?
Thermal
What is shown in a Sankey diagram?
Useful and non-useful energy transfers
What units are used to measure energy?
Joules, J
What does the thickness of the arrows in a Sankey diagram show?
The amount of energy transferred
Define efficiency.
How much of the energy transferred to a system is transferred usefully
How do you calculate efficiency?
(Useful output ÷ Total input) x 100
If a light bulb is described as 60% efficient, what does this mean?
It transfers 60% of the total energy input as useful energy (light)
What is a multicellular organism?
Organism with more than one cell
What is a tissue?
Collection of cells which work together to perform a function
Name a human organ system.
Digestive, circulatory, nervous
How does size of an organism affect its SA: V ratio?
Bigger the organism the smaller its SA: V ratio
How is surface area of a cube calculated?
Length x width x 6 (number of sides)
How is volume of a cube calculated?
Length x width x height
Give 2 adaptations of exchange surfaces.
Good blood supply, thin membrane, large surface area
Give two examples of exchange surfaces in humans.
Alveoli and villi
Name 4 fuels we may use at home.
Coal, wood, oil and natural gas
What do fuels react with during burning?
Oxygen
What unit of measurement is used for the energy found in foods?
Kilojoules or calories
How much energy will 2400 calories provide your cells with?
10 kJ
What happens if you consume too many calories?
Stored as chemical energy in fat cells
What energy store is in food and fuel?
Chemical
What are carbohydrates broken down into during digestion?
Glucose
Name 3 processes your body uses energy for.
Grow, move, reproduce, keep us warm, repair
What store of energy does a moving object have?
Kinetic energy
What do fuels react with when they are burned?
Oxygen
What type of organism eats both plants and other animals?
Omnivore
True or False: “The stamen is the male part of the plant”
TRUE
What colour will universal indicator turn in a strong acid?
Red
What is a neutralisation reaction?
An acid reacts with a base (or alkali)
What is power?
The rate energy is transferred or work is done over time
Describe what a power rating of 350 W means in words.
350 joules of energy is transferred per second
How do we convert from W into kW?
Divide by 1000
How many W are there in 3 kW?
3 x 1000 = 3000 W
True or false? “Power can also be given the units Joules per second (J/s).”
TRUE
State the equation that links energy transferred, power, and time.
Power = Energy transferred ÷ Time
What unit of time do we use when calculating power?
Seconds
If a 200W oven releases 60W of thermal energy, what is its efficiency?
30%
What 2 charges does an energy bill contain?
Standing charge, the cost of energy per unit
What unit of measurement do energy suppliers use?
Kilowatt-hours (kWh)
How many joules are in 1 kWh?
3,600,000 Joules
How many J of energy is transferred in 0.5 kWh?
1,800,000 Joules
How is the equation for calculating energy similar to the equation for power?
Both have same variables – energy transferred, power, time
How is the equation for calculating energy different to the equation for power?
Use different units of measurement – kWh, kW, hours
What is the equation for calculating cost of energy?
Cost (p) = Energy transferred (kWh) x Cost per kWh of energy (p)
Define renewable.
Can be replenished or replaced
Name two examples of renewable energy resources.
Wind, waves, tides, sunlight, geothermal
What energy store causes wind turbines to turn?
Kinetic
Other than being renewable, state one benefit of wind turbines.
No fuel costs and no harmful polluting gases are produced
Which renewable resource transfers energy from a gravitational energy store?
Hydroelectric
How are waves used to generate electricity?
Kinetic energy of waves turns turbine
State one negative impact tidal barrages have on the environment.
Destroy the habitats of estuary species, including wading birds
How does hydroelectric power contribute to global warming?
Rotting vegetation underwater releases methane, which is a greenhouse gas
What is geothermal energy?
Heat from underneath the Earth’s surface
Give two ways of harnessing geothermal energy.
Using hot water and steam from deep underground or using hot rocks to heat up cold water
Why can’t we use geothermal power in the UK?
Can only be used in certain areas
State the energy transfer that occurs in a solar cell.
Light 🡪 electrical
Why are solar cells also called photovoltaic cells?
Photo means light, volt is the measurement of electrical energy
What is the difference between a solar cell and a solar panel?
Solar panels use thermal energy, solar cells use light
How does a solar panel reduce our dependence on gas central heating?
Do not have to burn gas to heat up water in a boiler
Why can solar power sometimes be an unreliable energy resource?
Does not work at night or when cloudy
Define non-renewable.
Cannot be replenished and will run out
Give 3 examples of fossil fuels.
Coal, oil and natural gas
How are fossil fuels formed?
Dead plants and animals are buried over millions of years
What energy store is found in fossil fuels?
Chemical
How can we use the energy store in fossil fuels to generate electricity?
We burn them to release thermal energy, which heats up water into steam and this turns turbines
Apart from being non-renewable, what is the major drawback of fossil fuels?
They contribute to global warming
Why might people not want to live near a nuclear power station?
There is a risk of a nuclear melt down
Give an example of the fuel used in a nuclear power station.
Uranium
What does GPE stand for?
Gravitational potential energy
What does GPE mean?
An energy store of objects that are raised within a gravitational field (meaning that they can fall)
What is kinetic energy?
Energy stores of moving objects
What unit is energy measured in?
Joules
State the equation that links GFS, GPE, height and mass.
GPE = GFS x Height x Mass
State the equation that links kinetic energy, mass and speed.
Kinetic energy = 0.5 x Mass x Speed²
What is the GFS on Earth?
10 N/kg
What is an elastic material?
A material that can be stretched or compressed
How is elastic deformation different to inelastic deformation?
During elastic deformation, the material returns to its original shape. During inelastic deformation, it does not
What does EPE stand for?
Elastic potential energy
What is EPE?
An energy store of all elastic materials
State the energy transfer when a compressed spring is released.
Elastic -> Kinetic
What does the spring constant of a material tell us?
How stretchy an object or material is
State the units for spring constant.
Newtons per metre (N/m)
State the equation for calculating EPE.
0.5 x spring constant x extension²
