Flashcards in Conservation of energy and power Deck (56):
Can energy be destroyed?
NO ENERGY CAN NEVER BE DESTROYED
If energy cannot be destroyed, what is the principle/rule of energy?
Energy can be transferred usefully, stored or dissapated but can never be destroyed or created
When you transfer energy is all of it transffered usefully?
No, some energy is always dissipated when energy transfer takes place, called 'wasted energy'
If a cold spoon is dropped into a insulated flask of hot soup, which is then sealed what happens in terms of energy in this closed system?
energy is transferred from the theermal energy store of the soup to the useless thermal energy store of the spoon, causing the soup to cool down slightly, energy transfers have happened within the system but no energy has left the system so the net change is 0
What is power?
Power is the rate of 'doing work' or energy trasnfer
How do you measure power?
Power is measured in watts. One watt = 1 joule of energy transferred per second
What are the equation for power in terms of energy?
Energy Transferred (Joules)
Work done (Joules)
How can we reduce wasted energy?
Lubricating frictional forces
How does lubricating minimise wasted energy transfer?
They reduce friction between two moving friction forces, which reduces the amount of energy dissipated
What is thermal conductivity?
Is a measure of how quickly energy is transferred through a material via vibration and collision with other particles. Materials with a high thermal conductivity transfer energy between their particles at a faster rate
What happens in terms of particles and density when conduction occurs?
the particles are free to move and are moving faster which means the space between the particles increases, which means the density of the region to decrease
How does insulation minimise wasted energy transfer?
It reduces the rates of convection and conduction inside the thing your insulating
What is convection heating?
when liquids and gases flow the warmer and less dense part of the gas or liquid will rise to the top while the more dense and cooler part sinks to the bottom, so the energetic particles move away from hotter regions to cooler regions
What is efficiency
How good a device is at making sure as much energy input is transferred into a useful energy store not a waste one
How do you make a device more efficient
What is the equation for efficiency?
Useful output energy(or power) transfer
Total input energy(or power) transfer
Can a device be 100% efficient and if there is what is it?
Only device 100% efficient is an electric heater, as all energy being transferred goes to the thermal energy store anyway which is what that devices purpose is. Most devices waste energy store is heat (e.g. a computer)
Where does all energy eventually end up?
THERMAL ENERGY STORE
Define what a non-renewable energy source is in terms of science?
Are fossil fuels and nuclear fuel (uranium and plutonium)
They are fuel sources that will eventually run out, and cause harm to the environment
Define what a renewable energy source is
They are energy sources that will never run out, and they can be replenished as it is being used
What are the features of a non renewable energy source
They will run out some day
They do damage to the environment
they are all naturally occurring
What are the features of a renewable energy source
They will never run out as the energy can be renewed as it is used
They cause visual and noise pollution and don't release poisonous gases.
They don't provide as much energy as non renewable
Sometimes they can be unreliable as they depend on the weather
Name some non renewable energy sources
Name some renewable energy sources
The sun(solar power)
How are non renewable energy sources used in transport?
Petrol and Diesel powered vehicles(most cars)
Coal in old fashioned steam trains
How are renewable energy sources used in transport?
Vehicles that can run on pure biofuel or a mix of it and petrol/diesel
How are non renewable energy sources used for heating your home
Natural gas is the most widely used fuel for heating homes in the UK. The gas is used to heat water, which is then pumped into radiators throughout the house
Coal is commonly burnt in fireplaces
Electric heaters which use electricity from non renewable energy sources
How are renewable energy sources used for heating your home
A geothermal heat pump uses geothermal energy resources to heat buildings
Solar water heaters work by using the sun to heat water which is then pumped into radiators in the building
Burning bio-fuel or using electricity generated from renewable resources can also be used for heating
How does the wind generate energy
Lots of wind turbines are put up in exposed places such as coasts and moors
When the wind catches the turbine it spins the turbine and turns a generator
What are the benefits to wind power
There is lots of wind
There's no pollution created
Minimal running costs
No permanent damage to the landscape
What are the disadvantages to wind power?
Spoil the landscape while they are there
turbines stop making power when the wind stops, cant increase the supply
initial costs are quite high
How does solar power generate electricity?
The solar cells generate an electric current when the sun hits them, best used for small appliances that don't require much power like watches or calculators
What are the benefits to solar power on a large scale?
Used in deserts or remote places where there's not much option for alternatives, makes use of the land
There is no pollution
it is a very reliable source as you know there will always be sun during the day, even if its cloudy its still effective
running costs are almost nothing
What are the disadvantages of solar power
You cant increase the power output when there is extra demand
High initial cost
usually can be used on a relatively small scale
How does geothermal power generate electricity
possible in volcanic areas or where hot rocks lie quite near to the surface. Uses heat to heat up water and as it rises it turns a turbine
What are the benefits of geothermal power?
Little damage to the environment
can heat buildings directly
What are the disadvantages to geothermal power
the cost of setting up a geothermal power station are high compared to the amount of energy it makes
hard to find suitable locations
How does hydro-electric power work?
Usually stations are built on a reservoir or a fast flowing river and as water flows through it, it would generate electricity
What are the advantages of hydro electric power?
It generates no pollution
can immediately cope with increase in the demand by letting more water flow
Reliable except if there's a drought
Minimal running costs
can be used on the small scale and in remote areas
What are the main disadvantages of hydro-electric power?
Large impact on destruction of habitats and the river quality
Valley gets flooded destroying homes
what is wave power?
lots of small wave powered turbines are located around the coast, and they are connected to a turbine
What are the benefits to wave power?
there is no pollution
no fuel costs
minimal running costs
useful on the smaller scale
What are the disadvantages to wave power
disturb wildlife and their habitats
spoil views and are hazardous to boats
cant be used on the large scale
What is tidal power?
it is when there is a tidal barrage built across a river estuary, as the tide comes In it fills up the estuary and it flows through at a controlled speed and turns a turbine which turns a generator
What are the benefits of tidal power?
no fuel costs
minimal running costs
can generate lots of power
What are the disadvantages of tidal power
Initial costs are moderately high
disturbs wildlife and destroys habitats when built
Amount of power made is variable
hard to find suitable estuaries
spoil the view
What is biofuel?
bio-fuels are renewable energy sources created from plants or animal faeces, they can be solid, liquid or gas and can be burnt to produce electricity and run cars in the same way fossil fuels can
What are the benefits to biofuel?
They are carbon neutral(only true if the rate of use same as rate of growth of plants)
reliable- as any crop can be used or any poo short time needed to grow new crops/poo
Can be stored for use
act similarly to fossil fuels
What are the disadvantages to biofuels?
high refining cost
demand cant be met for food also
deforestation has to happen to make space for production and growth of biofuels further hurting the environment also increase CO2 and methane emissions
cant respond to immediate energy demands
What are the benefits to non-renewable sources of energy?
They are very reliable, and can keep up to current demand
can be extracted as they are being used
running costs aren't expensive
low fuel extraction costs
cost effective way to produce energy
What are the disadvantages to non-renewable sources of energy?
CO2 released into atmosphere creating a greenhouse affect that contributes to global warming
Sulfur dioxide released which creates acid rain (can be reduced by taking out the emmisions)
Mining for the resources ruins the landscape
Oil spillage causes serious environmental problems
Nuclear power is clean but the waste is very harmful and hard to dispose of properly
Nuclear fuel is cheap (Uranium) but the overall cost is high due to the cost of the power plant and the final decommissioning
Nuclear always has the potential of having a large disaster such as Fukushima in Japan
What was the reason for increasing demand in energy in modern times?
Population growth and the increasing amount of appliances that rely on electricity
Why is our reliance on electricity decreasing?
Appliances are becoming more efficient and use energy more responsibly
Also trying to use more renewable energy sources
How is most of our power made today?
By non renewable sources such as, coal, gas, oil and nuclear
How else do we use energy apart from electricity?