Studied by 0 peopleWhat are bio-fuels?
renewable energy sources created from plant products or animal dung.
How are bio-fuels used?
Burnt as a solid, liquid or gas to produce electricity or to run cars the same way as fossil fuels
What are the positives of bio-fuels?
Carbon neutral if plants are grown at the same rate they are burnt
Reliable
Crops take a short time to grow
Can be stored fr future use or demand
What are the negatives of bio-fuels?
Cost to refine bio-fuels is very high
Limited access to space and water makes the crops available limited
Loss of habitats to make space
Decay and burning cause Carbon dioxide and methane emissions
Why are non-renewable resources reliable?
meet the current demand for power
power plants can respond quickly to changes in demand
cost effective
What are the problems with non-renewable resources?
Slowly running out
High set up costs
Bad environmental impact
What are the environmental problems of non-renewable resources?
Releases carbon dioxide which contributes to the greenhouse affect and then global warming
Burning coal and oil releases sulphur dioxide which causes acidic rain ( can be reduced if sulphur is removed before burning )
Coal mining messes up the landscape and it ruins the view
Oil spillages cause serious environmental problems severely affecting wildlife and sea-life
Nuclear waste is dangerous and hard to dispose of
Nuclear power has the risk of catastrophe
What is the current trend of energy resource use?
heavily depend on fossil fuels
The electricity demand is huge due to population increases
Electricity use is slowly decreasing due to more efficient appliances
Fossil fuels and nuclear power is used for electricity, heating, gas and cooking
What are the current trends for renewable energy resources?
Knowledge of fossil fuels being damaging to the environment is common
Aware non-renewables are running out
People think its better to learn to live without non-renewables before they run out
Pressure on governments from the public is causing introduction of targets for renewable resources
electric cars and hybrids are becoming more popular due to the public changes in a attitudes
How are reliability, money and politics limiting the use of renewable resources?
Building new renewable resources is costly do to and more expensive for everyone
Many people won’t be able to afford renewable sources
Disturbances from the sources may cause future protests making the decision unethical
Some renewable sources are not reliable or do not make enough power to supply the demand in the world
renewable resources are not reliable, popular or cost effective enough to become dependable on them
Politicians have too many varied opinions to make steady progress
How does hydro-electric power work?
Requires the flooding of. valley by building a big dam. Water is allowed out through turbines
What are the positives of hydro-electric power?
Can provide a immediate response to increase in demand for electricity
Minimal running costs
Great for small scale electricity in remote areas
No fuel costs
What are the negatives of hydroelectric power?
Big impact on environment: rotting veg, release of methane and carbon dioxide, loss of habitat
Ugly when they dry up
Not reliable in times of drought
High initial costs
How is wave powered energy produced?
Uses lots of small wave powered turbines around the coast. The waves move the turbines that are connected to a generator
What are the positives of wave energy?
no pollution
No fuel costs
Minimal running costs
useful to small islands
What are the negatives of wave energy?
disturbed the sea bed and marine habitats
ruins the view
hazard to boats
Unreliable because tides die down with the wind
High initial costs
Cab’t provide energy on a large scale
What is a tide barrage?
big dams built across river estuaries with turbines in them
How does a tide barrage work?
As the tide comes in, it fills up the estuary, the water is then allowed out through the turbines at a controlled speed
How are tides produced?
By the gravitational pull of the sun and the moon
What are the positives of using tidal energy?
No pollution
Reliable: always be tides at similar heights twice a day
no fuel costs
minimal running costs
can generate a significant amount of power
What are the negatives of using tidal energy?
preventing free access for boats
spoiling the view
altering the habitat
The height of the wave isn’t always the same which can effect the amount of energy produced
Initial costs are moderately high
What is used to generate wind power?
Lots of wind turbines in exposed places like moors or around coasts
How do wind turbines generate power?
Each turbine has a generator inside of it that produces electricity
What are the positives of wind turbines?
No pollution
No permanent damage to landscape
Can be removed without damage being done
No fuel costs
Minimal maintenance costs
What are the negatives of wind turbines?
Spoil the view: requires 1500 turbines to replace one coal station
Noisy
Impossible to increase supply when demand is increased
Only produce electricity 70-85% of the time
Expensive initial costs
How do solar panels work?
Generate electrical currents directly from sunlight
Where does solar energy work best?
To charge batteries that don’t use much electricity
In remote places to power road signs and satellites
What are the positives of solar panels?
No pollution
Very reliable in sunny countries
Running costs are free
Almost no running costs
Still effective in cloudy countries
What are the negatives of solar panels?
Only works during the daytime
Can’t increase the power output according to demand
High initial costs
Doesn’t work effectively on a large scale
What is geothermal power?
Energy from volcanic areas, where hot rocks lie close to earths surface, and the slow decay of various radioactive elements
How is geothermal energy used?
To generate electricity or heat buildings directly
What are the positives of geothermal power?
free
reliable
little damage tot he environment
What are the negatives of geothermal power?
not many suitable locations
Cost is high for the energy it produces
What is a non-renewable resource?
energy resources that will run out one day
they all do damage to the environment
reliable sources of energy
What are renewable energy resources?
Coal
Oil
Natural gas
What are non-renewable energy resources?
They will never run out and can be reused
Do less damage than non-renewable energy sources
Don’t provide much energy and are dependant on the weather
What are some examples of renewable energy resources?
Solar
wind
water waves
Hydro-electricity
bio-fuel
tides
Geothermal
How are non-renewable resources used in transport?
Petrol and diesel powered vehicles
Coal is used to produce steam for old fashioned steam trains
How are renewable resources used in transport?
Vehicles that run on bio-fuels
How are non-renewable resources used for heating?
Natural gas is used to heat water and is pumped through radiators in homes
Coal is burnt in fireplaces
Electrical uses use electricity generated from non-renewable energy resources
How are renewable resources used for heating?
A geothermal heat pump uses geothermal energy resources to heat up buildings
Solar water heaters use the sun the heat water which is pumped through radiators to heat a building
Burning bio-fuels or using electricity generated from renewable resources can be used for heating
How can you improve the efficiency of energy transfers?
Insulation
What is the formula for efficiency if you know the input and output of energy transfer?
What is the formula for efficiency is you know the power input and output?
Is useful output energy usually equal to total energy input?
No, energy is usually transferred to useless thermal energy stores
Give an example of a device that is 100% efficient in its energy transfers and why?
Electrical heaters- all energy in the electrostatic energy store is transferred to the useful thermal energy stores
What do frictional forces cause and where are they usually found?
Whenever something moves there is usually at least one frictional force acting against it.
This causes some energy in the system to be dissipated
When can lubricants be used to reduce friction?
When objects are being rubbed together and cause friction
What is an example of a lubricant?
A liquid that can flow easily between objects and coat them like oil
How does having thick walls in a house reduce heat loss?
Must be made of a material with low thermal conductivity
The thicker the walls, the lower their thermal conductivity and the slower the rate of energy transfer will be.
What are cavity walls and how do they work to prevent heat loss in houses?
An inner and outer wall with an air gap in the middle. The air gap reduces the amount of energy transferred by convection in the wall cavity
What is cavity wall insulation and how does it work?
The cavity wall air gap is filled with a foam that can reduce the energy transfer by convection in the wall cavity
How do double-glazed windows reduce heat loss in houses?
They have an air gap between the two sheets of glass to prevent energy conduction through the windows
Name 4 examples of thermal insulation to prevent heat loss in houses.
cavity walls/cavity wall insulation
loft insulation
double-glazed windows
Draught excluders
Explain a method to investigate the effectiveness of materials as thermal insulators.
Boil water in a kettle. Pour some water into a sealable container to a safe level. Measure the mass of the water in the container.
Use a thermometer to measure the initial temperature of the water.
Seal the container and leave it for 5minutes. Measure this time using a stopwatch
Remove the lid and measure the final temperature of the water
Pour the water away and allow the container to cool to room temperature
Repeat this experiment, but wrap the container in a different material once it has been sealed. Make sure to use the same mass of water and initial temperature each time
What is conduction?
the process where vibrating particles transfer energy to neighbouring particles
In what state does conduction usually occur?
Solids
Explain the process of conduction.
Energy transferred to an object by heating is transferred to the thermal energy store of the object. This energy is shared across the kinetic energy stores of the particles in the object
The particles in the part of the object being heated vibrate more and collide with each other. These collisions cause more energy to be transferred between particles kinetic energy stores
This process continues throughout the object to the other side until its eventually transferred to the thermal energy stores of its surroundings.
What is thermal conductivity?
a measure of how quickly energy is transferred through a material through conduction.
What is convection?
where energetic particles move away from hotter to cooler regions
In what states does convection usually occur in?
Liquids and gases
Explain the process of convection.
Energy is transferred by heating to the thermal energy stores of a liquid or gas. This energy is shared across the kinetic energy stores of the gas or liquids particles
When you heat a region of gas or liquid the particles move faster and the space between individual particles increases. This causes the density of the region being heated to decrease.
Because liquids and gases can flow, the warmer and less dense region will rise above denser, cooler regions. If there is a constant heat source, a convection current can be created
Use a radiator as an example to explain how a convection current is created.
Energy is transferred from the radiator to nearby air particles by conduction
The air by the radiator becomes warmer and less dense
The warm air rises and is replaced by cooler air which is then heated by the radiator
At the same time the previously heated air transfers energy to the surroundings. its Colls, becomes denser and sinks
This cycle repeats causing flow of air to circulate around the room causing a convection current
What is the conservation of energy principle?
Energy can be transferred, stored or dissipated but can never be created or destroyed
What are the two ways energy can be transferred?
into useful energy stores
dissipated into wasteful energy stores
Explain the transfer of energy in a cell phone in terms of useful and un-useful energy.
When you use a phone energy is usefully transferred to the chemical energy store of the battery, but some energy is dissipated to the thermal energy store of the phone
Explain an example of energy transfer in a closed system.
cold spoon in soup thermos:
Cold spoon dropped into insulated flask of soup then sealed
forms a closed system if perfect insulator
from thermal energy of the soup to useless thermal energy store of the spoon
causing soup to cool down slightly
What is power?
the rate of energy transfer or the rate of doing work
What is the equation for power?
P=power( watts/W)
E=energy transferred(J)
t=time(s)
W=work done (J)
How does an object gain or lose energy?
Energy is transferred from one energy store to another
What are the energy stores?
thermal
kinetic
gravitational kinetic
elastic potential
chemical
magnetic
electrostatic
nuclear
Name the 4 ways energy can be transferred:
mechanically
electrically
by heating
by radiation
How does the transfer of energy work in a system?
When a system changes:
energy is transferred into or away from the system
to different objects
between different types of energy stores
What is a closed system?
Neither matter nor energy can enter or leave. The net change in the total energy of a closed system is always zero.
Explain how energy is transferred by heating.
Energy is transferred to the water by heating into the waters thermal stores causing the temperature to rise
Or if you view it as a two-object system
Energy is transferred electrically to the thermal energy store of the water, which transfers energy by heating into the waters thermal energy stores
Explain how energy is transferred when a person throws a ball.
the initial force a person uses to throw the ball causes energy to transfer from the chemical energy store of the persons arm to the kinetic energy store of the ball and the arm.
Explain how the work done from dropping a ball causes energy to transfer.
a ball dropped from a height is accelerated by gravity
The gravitational force does the work
Causes energy to be transferred from the balls gravitational potential energy store to its kinetic energy store.
Explain how the work done for a car to stop from the brakes causes energy to be transferred.
The friction between a car’s brakes and its wheels does work as it slows down
It causes energy to transfer from the wheel’s kinetic energy store to the thermal energy store of the surroundings
Explain how the work done when a moving car crashes into a stationary object causes energy to transfer.
The normal contact force between the car and the object does work
It causes energy to be transferred from the cars kinetic energy store to other energy stores such as
the elastic potential and thermal stores of the object and the car body
Some energy may be transferred away by sound waves
Describe the energy transfers that occur when wind causes a windmill to spin.
The energy is transferred mechanically
the winds kinetic energy store is transferred to
the windmills kinetic energy stores causing it to spin.
What is the formula for kinetic energy?
Kinetic energy(J) = 0.5 x mass(kg) x speed²(m/s)²
What is the formula for gravitational potential energy?
GPE (J) = Mass (kg) x gravitational field strength (N/kg) x height (m)
What is the elastic potential energy equation?
elastic potential energy (J) = 0.5 x spring constant (N/m) x extension ² (m)
How does air resistance effect th energy transfer of a falling object?
Air resistance acts against all falling objects causing some energy to be transferred to other energy stores such as the thermal energy stores of the object and surroundings.
A 2.0 kg object is dropped from a height of 10m
Calculate the speed of the object after it has fallen 5.0 m, assuming there is no air resistance.
Give your answer to 2 significant figures.
G=9.8 N/kg
(5 marks
Height change is 5m so the energy transferred from the gravitational potential energy store is Ep= mgh=2 × 9.8 × 5=98J
Ek=98 J
Ek=0.5mv² so v² = 2Ek/m
= (2 × 98) /2 | v= √98=9.899…
= 9.9m/s
What happens to the energy transfer between stores of a falling object without air resistance?
Energy lost from gpe store = energy gained in kinetic energy store
What is specific heat capacity?
the amount of energy needed to raise the temperature of 2kg of a substance by 1.c
What is the equation for specific heat capacity
Change in thermal energy(J)=mass(kg)specific heat capacity(J/kgC)temperature change(.c)
What is the practical to investigate specific heat capacity?
Measure the mass of a solid block and wrap it in an insulating layer to reduce the energy transferred from the black to its surroundings. Attach the heater and thermometer to the metal block in the two holes.
Measure the initial temperature of the block and set up the potential difference of the power supply to be 10V. Turn on the power supply and start a stop watch
When you turn on the power the current in the circuit dies work on the heater transferring energy electrically from the power supply to the heaters thermal energy store. This is then transferred to the materials thermal energy store by heating causing its temperature to increase
As the block heats up, take readings of the temperature and current every minute for 10 minutes. You should find that the current doesn’t change as the block heats up
Once you have enough readings, turn off the power supply and calculate the power supplied to the heater and how much energy has been transferred to the heater.
Plot a graph of the energy transferred to the thermal energy store of the block against the temperatures
Find the gradient of the straight part of the graph and calculate the specific heat capacity
You can repeat this with different materials to see how their specific heat capacities compare
What are the 2 holes in the solid material block for?
The heater and thermometer
Why do you insulate the block
To reduce the energy transferred from the block to its surroundings
What is the independent variable?
Time
What is the dependant variable?
The temperature of block
What should happen to the current as the temperature of the block increases?
The current should stay the same/not be affected
What equation do you use to calculate the power supplied to the heater?
P=VI
What equation do you use to calculate the energy transferred to the heater at each time of temperature reading?
E=Pt
Note 
Flashcard (187)