P1- Energy Flashcards
What is energy transferred by?
Energy stores
What are the eight energy stores?
Thermal energy stores Chemical energy stores
Kinetic energy stores Magnetic energy stores
Gravitational potential energy stores Electrostatic energy stores
Elastic potential energy stores Nuclear energy stores
What is it meant by system?
Single object or a group of objects
What happens when a system changes?
Energy is transfered
What are closed systems?
Systems where neither matter nor energy can enter or leave.
What is the net change in a closed system?
Zero
What is meant by work done?
Energy transferred
What is the initial force exerted by a person throwing a ball upwards?
Chemical
What is a ball dropped from a height accelerated by?
Gravity
What energy does a moving object have?
Kinetic energy
What two things does kinetic energy store depend on?
Mass & speed
What is the equation for kinetic energy?
E (j) =1/2 x mass(kg) x velocity^2 (m/s)
What does movement mean?
Energy in an object’s kinetic energy store
If something is moving what energy store does it have?
Kinetic energy
What changes the amount of kinetic an object has?
Mass and speed
How does the mass of an object change its speed?
The greater the mass the greater the speed
What is the formula for kinetic energy?
e=1/2mass x velocity(speed)^2
What energy store does a raised object have?
Gravitational potential
What does lifting an object in a gravitational field require?
Work
How does the height of an object change the gravitational potential energy?
The higher the object the more gravitational potential energy
What impacts an object in a g.p.e energy store?
- Mass
- Height
- strength of the gravitational field the object is in
Do falling objects also transfer energy?
Yes
When an object is falling what is the energy transfers?
Gravitational potential energy store is transferred to its kinetic energy store
In real life do all falling objects have air resistance?
Yes
(For a falling object where there is no air resistance) Energy lost from the g.p.e store=?
Energy gained in the kinetic energy store
What can stretching transfer the energy into?
Elastic potential energy stores
What can stretching or squashing transfer energy into?
Elastic potential energy
Elastic potential(j) =
1/2 spring constant (N/m)x extension^2(m)
Do all materials have the same specific heat capacities?
No
If a material needs lots of energy to gain heat does it mean it also transfers lots of energy to cool down?
Yes
Define specific heat capacity?
The amount of energy required to raise the temperature of 1kg by 1 degree celsius
What is the equation for specific heat capacity?
Change in thermal energy (j)= mass(kg) x specific heat capacity(j/kg degrees celcius)
What equipment do you need to investigate specific heat capacity?
- A solid material(e.g copper) with two holes in it
- Heater
- Thermometer
- Ammeter
- Power supply
Can energy be destroyed?
No
What is the conservation of energy principle?
Energy can be transferred usefully, stored or dissipated, but can never be destroyed
When energy is transferred between stores is all of the energy transferred usefully?
No
What is the word used to describe what happens to energy that isn’t transferred usefully?
Dissipated/ waste energy
Is a mobile phone a system?
Yes
When you use a phone how is energy usefully transferred into battery?
Chemical energy
What is an example of dissipated energy in a mobile phone?
Thermal energy
What is a closed system?
A type of thermodynamic system where mass is conserved within the boundaries of the system, but energy is allowed to freely enter or exit the system.
What is power ‘the rate of’
‘Rate of doing work’/’Rate of energy transfer’
What is power measured in?
Watts
One watt=
1 joule of energy transferred per second
Powe (w)=
Energy transferred(j)/time(s) or work done(j)/time(s)
Where does conduction occur?
In solids
What is conduction the process of?
Vibrating particles transfer energy to neighbouring particles
If something is transferred to an object by heating what store does it go to?
Thermal wich is shared across the kinetic energy stores of the particles in the object
Do the particles in an object that is being heated vibrate more and collide with each other?
Yes
What energy do colliding particles cause to be transferred between each other?
Kinetic
Where does convection occur?
Liquids and gases
What happens in convection?
Energetic particles move away from hotter to colder regions
How is energy transferred in convection?
By heating to the thermal store of the liquid or gas. The energy is shared across the kinetic energy stores of the liquid or gas particles
Are the particles in solids able to move?
No
Are the particles in liquids able to move?
Yes
Are the particles in gasses able to move?
Yes
What happens to the particles in a region that are heated up in a liquid?
They move faster
What happens to the gaps in between the particles
when a liquid or solid is heated?
They increase
Does the density of a gas or liquid increase when it is heated?
No
Radiators create convection..?
Currents
How is energy transferred from a radiator to nearby air particles?
Conduction
Where does warm air go?
Up
What are ways u can reduce the amount of energy scampering off to a completely useless store?
Lubricant and thermal insulators
What does lubricant do?
Reduce frictional force
Whenever something moves how many fictional forces act against it?
At least one
What do insulators reduce the rate of?
Energy transferred by heat
What are things you can do to reduce the amount of energy that escapes the house?
-Have thick walls. The thicker the walls are the lower their thermal conductivity the slower the rate of energy transfer( so the building will cool more slowly
- Cavity walls which have an inner and outer walls which have a gap in between
- Loft insulation
- Double-glazing windows
- Draught excluders around doors and windows reduce energy transfers by convection
Do most energy transfers involve some waste energy?
Yes
What is the main useless energy store?
Thermal energy
The less energy wasted what is the product?
More efficient
How can you improve the efficiency of an object?
- Insulating
- Lubricating
- Streamline
What is the equation for efficiency?=
Useful output energy/Total input energy transfer or useful power output/total power output
Is any device 100% efficient?
No (apart from electric heaters because all the energy is transferred into useful thermal energy stores
What are energy stores (renewable and non-renewable) generated to make?
Electricity
What are the three main fossil fuels?
- Coal
- Oil
- (natural) Gas
What are 7 renewable resources?
- Wind
- Water waves Hydro-electricity
- The sun (solar)
- Bio-fuel
- Tides
- Geothermal
Do most renewable reasources damage the environment?
Yes but it is less nasty then non-renewable ways
What are non-renewable energy resources for transport?
- Petrol and diesel use fuel created by from oil
- Coal
What are renewable energy resources for transport?
Bio-fuels
What are non-renewable energy resources for heating?
- Natural gas
- Coal
- Electric heaters
What are non-renewable energy resources for heating?
- Geothermal
- Solar water heaters
- Bio-fuel
Where are turbines often placed?
Moors or around coasts
Where does the pollution come from in wind turbines?
When the are being manufactured
How many turbines do you need to replace 1 coal fire?
1500, which spoils scenery
What are cons of wind power?
- Spoils views
- You need a lot of wind power for the same amount of energy as non-renewable resources
- It isn’t always wind ( they only produce energy 70-85% of the time)
- The initial cost is high
What are pros of wind power?
- It is renewable
- There are no fuel costs and minimal running costs
- There’s no permanent damage to the landscape
What are pros to solar power?
- They are often the best option to be used in calculators and watches which don’t use much energy
- There’s no pollution
- In sunny countries it is a very reliable source
- Once it has started running the cost is basically nothing
- They can also be used in cloudy countries
What are cons of solar power?
- They only run at day time
- You can’t increase the energy output for extra demand
- The initial costs are high
Where is geothermal energy available?
In volcanic areas or where hot rocks lie near the surface?
Does geothermal energy damage the environment?
No very much
What is the main drawback of geothermal energy?
there aren’t many sustainable locations for power plants, and that the cost of building a power plant is often high compared to the amount of energy it produces
What kind of water does hydroelectric power use?
Falling
What does hydroelectric power use, flooding…
Valley by building or big damn
Is there any pollution with hydroelectric power?
No
What is a negative impact that hydroelectric power has on the environment?
- Due to the flooding of the valley rooting vegetation releases methane and C02.
- Possible loss of habitat
How fast can hydroelectric power respond to increased demand?
Almost immediately
Are the initial costs high for hydroelectric power?
Yes
Are there any fuel costs to hydroelectric power?
No
Are the running costs high for hydroelectric power?
No
Is hydroelectric power good for big areas?
No
What is wave power?
Lots of little wave-powered turbines
Where are lots of little wave-powered turbines located?
By the coast
What are cons to wave power?
- Disrupting seabeds and habitats
- Spoiling the view
- Hazard to boats
- They are a bit unreliable
- Initial costs are high
- Can’t provide energy on a large scale
What are pros to wave power?
-It can be very useful
-No pollution
-
What are tidal barrages?
Big dams built across river estuaries, with turbines in them. As the tide comes in it fills up the estuary. The water is then allowed out through turbines at a controlled speed?
How are the tides produced in wave power?
The gravitational pull of the Sun and Moon
What are the main problems of tidal barrages?
Preventing free access by boats, spoiling the view and altering the habitat of wildlife
Are thwle tides reliable for energy?
Yes
Can the height of the tide variable?
Yes, this is a drawback because lower (neap) tides will provide significantly less energy than bigger ‘spring’ tides.
What are additional costs to tidal barrages?
Minimal running costs
Are the initial costs high of tidal barrages?
Yes
Are there fuel costs with tidal barrages?
Yes
What are brio-fuels made from?
Plants and waste
Are bio-fuels renewable?
Yes
Are bio-fuels carbon neutral?
Yes
Are bio-fuels reliable?
Yes
Can bio-fuels respond to immediate demands?
No
Is there a cost to refine bio-fuels?
Yes, it ‘s high
Do bio-fuels produce CO2?
Yes
Can bio-fuels cause a loss of habitat?
Yes
Are fossil fuels reliable?
Yes
Is nuclear energy reliable?
Yes
Is running a nuclear power plant expensive?
No
Is the cost of setting up a nuclear power plant expensive?
Yes
Is extracting nuclear energy expensive?
No
What are 7 disadvantages of non-renewable energy?
- Coal, oil and gas release CO2 into the atmosphere when they’re burned. This creates the greenhouse gas effect
- Burning coal and oil causes realeses sulfur dioxide, which causes acid rain- which can be harmful to trees and soils and can have far-reaching effects in ecosystems
- Coal mining makes a mess of the land scale, especially “open cast mining”. As with many energy resources, the view can be spoilt by fossil fuel power plants
- Oil spillages cays serious environmental problems, affecting mammals and birds that live in and around the sea
- Nuclear power is clean but the nucleur waste is very dangerous and difficult to dispose of
- Nuclear fuel is cheap but the overall cost of nuclear power is high
- Nuclear power always carries the risk of a major catastophe
Where is most of our energy from?
Fossil fuels and nuclear energy
Why are energy providers to use renewable energy sources?
Fossil fuels are more cost efficient
Describe the energy transfers that occur when a liquid is heated using equipment
The current flowing throughthe immersion heaterdoes work The current flowing through the immersion heater does work, transferring energy electrically to the thermal energy store of the immersion heater. It is then transferred from the thermal energy of the immersion heater to the thermal energy store of the liqued
Define wasted energy
Energy transferred to a less useful energy store
State the units for Specific Heat
Capacity.
J/°C/kg
Joules/Degree Celsius/Kilogram
What is the definition of ‘Power’?
The rate at which energy is transferred
or rate at which work is done
State two equations for power. Give SI units for all
quantities involved.
ower = energy transferred/time
power = work done/time
Energy (J), Work Done (J), Time (s)
What is the unit of power?
Watt (W)
Two motors lift the same mass through
the same height. Motor A does this in
half the time of Motor B. Which
dissipates the most power?
Motor A.
The energy transferred is the same but
the time taken is less (P=E/t).
Describe the energy changes involved when a ball is
thrown upwards and then returns to its starting
position. Ignore air resistance.
● Upwards: KE is converted to GPE
● Peak: Maximum GPE, zero KE
● Downwards: GPE is converted to KE
KE (Kinetic Energy), GPE (Gravitational Potential Energy)
Describe the energy transfers for a bungee jumper.
● When falling, the GPE is converted to KE of
jumper
● As the cord tightens, KE is converted and
stored as Elastic Potential Energy (EPE)
● At lowest point, the jumper’s initial GPE
equals the EPE stored in the cord
Explain why a bungee jumper slows down once the
cord begins to stretch.
● Kinetic energy decreases since it is
converted to elastic potential energy
● Since KE is proportional to (velocity)²,
as KE decreases, so does velocity.
Give examples of chemical energy stores.
● Food
● Fuel (eg. wood, coal, petrol)
● Batteries
State 4 different stores of energy.
- Kinetic Energy
- Gravitational Potential Energy
- Elastic Potential Energy
- Chemical Energy
State the law of energy conservation.
Energy cannot be created or destroyed
(it can only be transferred into different
forms).
State any changes in the total energy of
a ball that is kicked, assuming that no
external forces act.
The total energy of the system remains
constant due to the conservation of
energy
What is waste energy?
The energy that is not used by the device
for its desired purpose.
Describe the energy changes that occur
in a filament light-bulb.
● Electrical energy is transferred into
light and heat energy
● Light is a useful energy form, heat is
waste energy
State two equations to calculate
efficiency.
=Useful Output Energy Transfer/Total
Input Energy Transfer
=Useful Power Output/Total Power
Output
How can the efficiency of a system be
increased?
- Reducing waste output (by
lubrication, thermal insulation etc.) - Recycling waste output (eg. recycling
thermal waste energy as input energy)
State the consequence for energy transfer of a
material with a igh thermal conductivity.
The rate of energy transfer through the
material is higher than for a material with
a lower thermal conductivity
Do double-glazed windows have a higher or lower
thermal conductivity than single-glazed windows?
Lower, meaning less energy transfers
through them.
What key factors affect the rate of cooling of a
building?
● The thickness of the walls
● The thermal conductivity of the walls
State three methods of reducing heat
loss in a building.
- Double glazing
- Loft and wall insulation
- Thicker walls
How can the efficiency of a mechanical machine with
moving parts be improved?
Lubricate any moving parts to reduce the
friction and therefore energy loss due to
heating.
How can the efficiency of a radiator be
improved?
Installing metal foil sheets behind the
radiator to reflect the heat back into the
room rather than it being absorbed into
the walls.
How can the efficiency of boiling water in
a pan be improved?
By placing a lid on the pan to reduce the
heat loss from the top.
What is a renewable energy resource?
An energy source which can be
replenished as it is being used up.
Give four examples of renewable energy
resources.
- Wind Energy
- Hydro-Electricity
- Tidal Energy
- Solar Energy
Give an example of a non-renewable
energy resource.
Fossil fuels (for example coal, oil and gas).
What are the advantages of generating power using
gas rather than coal?
● Flexible Generation: Gas power
stations have short start-up times so
can be switched on/off more readily
● Lower emissions of carbon dioxide
State two disadvantages of using
renewable energy resources to generate
power.
● Output often determined by external factors
(like wind speed), so supply is uncertain
● Generating power through other means is
often more efficient and economically
beneficial
Explain the environmental impacts of burning fossil
fuels.
● Carbon Dioxide contributes to the greenhouse effect, and causes global warming ● Sulphur Dioxide leads to acid rain, which can damage buildings and crops
State three advantages of fossil fuels as an energy
resource.
- Reliable: Not dependent on external factors
so can generate power anytime - Can produce large amounts of energy for a
given quantity - Still relatively abundant, so cost-effective
State three advantages of nuclear
power.
- Very large amounts of energy for relatively
small quantities of fuel - Doesn’t release greenhouse gases and so
doesn’t contribute to climate change - Low fuel costs
State three disadvantages of nuclear
power.
- Produces nuclear waste which is harmful to
humans & must be safely stored for centuries. - Non-Renewable energy source
- Risk of nuclear accidents, which have fatal
consequences on humans and the
environment
How does hydroelectric power produce
energy?
● Rainwater collects behind a dam ● When this water is released, it is used to turn a turbine ● This turbine turns a generator which produces electricity
What are some disadvantages of using biofuels?
● When plants are burned or decay they release CO2
● In order to grow biofuels, you need to destroy land
which leads to problems because:
○ The land could have been natural habitats
○ Destroying land may involve burning plants growing
on it, which would release CO2
● Growing biofuels reduces the land available for growing
food
What are the advantages of tidal energy
sources?
● They do not produce greenhouse gases ● They are quite reliable, as tides happen twice a day ● They are cheap to run as tides are natural, and so are free
What are the disadvantages of
hydroelectric power?
● The dam may cause flooding
● It can cost a lot to install the required
infrastructure
What are some advantages of solar panels?
● They don’t cause harm to the environment ● They are a renewable resource ● They can be used in remote areas where other types of energy are less accessible
Give an example of a social factor which may act as
a deterrent for certain types of energy production.
● Visual Pollution
● Sound Pollution
(both of these are disadvantages of wind farms)
