1-Energy Flashcards
What does a system mean
A single object or group of objects that you r interested in
What happens when a system changes
Energy is transferred
What is a closed system
Neither matter or energy can enter or leave
How can energy be transferred
Heating
Doing work
Radiation
Electrically
What is the equation for kinetic energy
Kinetic energy(J) =1/2mass(Kg) x speed2 (m/s)2
Ek = 1/2mv*2
What is the equation for gravitational potential energy
g.p.e(J) = Mass(kg) x gravitational field strength (N/kg) x Height(m)
Ep = mgh
When there is no air resistance, what happens to a falling object’s energy stores
Energy lost from g.p.e store =
Energy gained in the kinetic energy store
What is the equation for elastic potential energy
Elastic potential energy(J) = 1/2 x spring constant (N/m) x extension*2(m)
Ee = 1/2ke*2
What is specific heat capacity
The amount of energy need to raise the temperature of 1kg of a substance by 1°C
What is the equation that links change in thermal energy to specific heat capacity
Change in thermal energy(J) = Mass(kg) x specific heat capacity(J/kg°C) x Temperature change(°C)
^E = mc^Ø
What is the conservation of energy principle
Energy can be transferred usefully, stored or dissipated but can never be created or destroyed
What is the power equation linking to energy transferred
Power(W) = Energy transferred(J) / Time (s)
P=E/t
What is the power equation linking to work done
Power(W) = Work done(J) / Time (s)
P=W/t
What is conduction
The process where vibrating particles transfer energy to neighbouring particles
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
What can convection go through
Gases and liquids because their particles can move
What can be used to reduce frictional force
Lubricants, like oil
What are some examples of thermal insulation used in housing
Cavity wall insulation,
Loft insulation,
Double glazed windows,
Draught excluders
How can the effectiveness of materials as thermal insulators be measured
Fill a sealable container with boiled water and record starting temp,
Wrap beaker in different materials a leave it for 5minutes each time,
Measure final temperature,
The lower the temperature change, the better the insulator
How can u calculate the efficiency for a energy transfer
Efficiency =
Useful output energy transfer / total input energy transfer
How can efficiency of a device in terms of power be calculated
Efficiency =
Useful power output / total power input
Examples of non renewable energy resources
Coal
Oil
Natural gas
Nuclear
Examples of renewable energy resources
Solar Wind Bio-fuel Hydro-electricity Geothermal Tidal Water waves
How do wind turbines work
Each turbine has a generator inside and the rotating blades turn the generator
What are advantages or wind turbines
Very little pollution (only in manufacture)
No permanent damage to environment
No fuel costs
Minimal running costs
What are disadvantages or wind turbines
Spoil views, Can be very noisy, Don’t work if wind stops, Impossible to increase supply if there is extra demand, Initial costs r high
Advantages of solar cells
Can be used in remote areas
Little pollution (only in manufacture)
Very reliable source in sunny countries
Very small running costs
Disadvantages of solar cells
Can’t increase power output when there is extra demand
Initial costs are high
Generate electricity on a relatively small scale
Advantages of geothermal energy
Reliable
Very little damage to environment
Can be used to generate electricity or heat homes directly
Disadvantages of geothermal
Not very many suitable locations
Cost of building a power plant is high compared to energy output
Advantages of hydro-electricity
Can provide an immediate response to an increased demand for electricity
Reliable
No fuel costs
Minimal running costs
Disadvantages of hydro-electricity
Big impact on environment due to the flooding of the valley
Ugly when the reservoirs dry up
Initial costs r high
Advantages of wave power
No fuel costs
Minimal running costs
Useful in small islands
Disadvantages of wave power
Disturbs the seabed Spoils the view Hazard for boats Fairly unreliable since the waves die out when wind stops Initial costs are high
How do tidal barrages work
Big dams built across river estuaries with turbines in them. As the tide comes in, it fills up the estuary and then the water is allowed out through turbines at a controlled speed
Advantages of tidal barrages
No pollution
Pretty reliable as the tide comes in twice a day
No fuel costs
Minimal running costs
Potential for generating a significant amount of energy
Disadvantages of tidal barrages
Prevent free access by boats Spoils view Alters habitat Smaller tides will produce significantly less energy than bigger ones Initial cost is high
How do biofuels work
Plant products or animal dung is burnt to produce electricity
Advantages of biofuels
Fairly reliable as crops take a relatively short time to grow
Supposedly carbon neutral but some debate over it
Disadvantages of biofuels
Cost to refine biofuels is very high
Large areas of forest have been cleared to make room to grow biofuels
Worry that crops specifically grown for biofuels leave no space or water for food crops
Advantages of non-renewable power
Reliable Power plants can respond to changes in demand Low running costs Fairly low fuel extraction costs Cost effective
What r the impacts of fossil fuels on the environment
Release lots CO2 into environment
Releases sulfur dioxide- acid rain
Coal mining destroys habitats
Oil spillages affect mammals and birds in that area
What r the disadvantages of nuclear power
Nuclear waste is difficult and dangerous to dispose of
Overall cost is high
Risk of catastrophes
Why r more renewable energy resources being used
People and government r becoming increasingly aware that non-renewables will run out,
Government set targets and put pressure on energy providers
Ethical and moral reasons
Electric and hybrid cars r increasing in popularity
How does money limit the use of renewables
Building new power plants is expensive so energy providers r reluctant to do this
The cost of switching will have to be paid either by customers in their bills or through taxes
New products like cars a expensive for customers
How does politics affect the use of renewables
People don’t want to live next to a power station and there r arguments over whether forcing them is ethical
How does reliability limit the use of renewables
Some, like wind, are not as reliable as fossil fuels and others can not increase power on demand.
