Energy Stores Flashcards
What are the 4 ways energy can be transfered?
Mechanically - when force does work on a object.
By heating - when energy is transferred from a hotter object to a cooler object.
Electrically - when a moving charge does work.
Radiation - when energy is transferred by e.g sound or light.
What are closed systems?
Systems where no matter (stuff) or energy can enter or leave.
(when a closed system changes, there is no net (overall) change in the total energy of the system.)
Energy can…
Energy can be transferred usefully, stored or dissipated, but NEVER be created or destroyed.
If a force moves an object what is being done?
Work is done.
What is the formula for finding the energy in an objects kinetic energy?
Kinetic energy = 1/2 mv^2
What energy store is anything that moves?
Kinetic energy.
- Energy is transferred to the kinetic energy store when an object speed up.
- Energy is transferred away from this store when a object slows down.
What energy store is raised objects?
Gravitational potential energy store.
- All objects raised above the ground gain energy in there gravitational potential energy store.
What is the formula for finding the energy in an objects g.p.e store?
G.p.e. = mgh
(Gravitational potential energy = mass x gravitational field strength x height.)
What energy store is stretching?
Elastic potential energy store.
1. Stretching or squashing and object can transfer energy to its elastic potential energy store.
Whats the formula for finding the elastic potential energy store of a stretched object?
E= 1/2 ke
(Elastic potential energy = 1/2 x spring constant x extension x2.)
what energy store can be transferred by heating?
Thermal energy store.
- As a material is heated, energy gets transferred to the thermal energy store.
- This causes temperature to increase.
What’s the formula for specific heat capacity?
Change in thermal energy = mass x specific heat capacity x temperature change.
What’s specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a material by 1 degree Celsius
What’s the practice for specific heat capacity?
What’s the formula to calculate power?
P = e / t
Power = energy transferred / time
What are ways you can reduce the amount of energy wasted?
1.Lubrication reduces frictional forces
2.insulation has a low thermal conductivity
3. Insulation is important for keeping buildings warm
How does lubrication reduce energy loss?
1.friction adds between all object that run together.
2. This causes some energy in the system to be dissipated.
How does insulation reduce energy loss?
- When a part of a material is heated, that part of the material gains energy.
- This energy is transferred across the material so that the rest I’d the material gets warmer.
- This is known as conduction.
- Thermal conductivity is a measure of how quickly energy is transferred by conduction throw a material.
- Materials with high thermal conductivity transfer lots of energy in a short time
- Materials with low thermal conductivity are called thermal insulators.
- Thermal insulators can reduce unwanted transfers by heating,
fill blanks (…) :
The …. energy wasted, the …. efficient the energy transfer is.
The less energy transferred, the more efficient the energy transfer is.
What are the 6 renewable resources?
- The sun (solar)
- Wind
- Water waves
- hydro-electricity
- bio-fuels
- tides
- geothermal
Describe wind turbines effects on the environment and how they work.
- Wind turbines are usually put up in open places.
- When the wind turns the blades, electricity is produced.
- They produce no pollution once they are built.
- And they do no permanent damage to the landscape (if removed goes back to normal).
- However, they are not as reliable as others
- They don’t produce electricity when wind stops
- Turbines are also stopped if wind is too strong (to stop damage)
- It also is impossible to increase supply when there’s demand for electricity.
Describe solar cells effects on the environment and how they work.
- Solar cells generate electricity directly from sunlight.
- They create no pollution once they are built.
- But quite a lot of energy is used to build them
- Solar power only generates electricity during the day.
- In sunny countries solar power is very reliable of energy.
- It still fairly reliable in cloudy countries.
- Like wind, you can’t increase the power output when there is extra demand.
Describe the effects of geothermal power on the environment and how they work.
- Geothermal power uses energy from the thermal energy store of hot rocks below the earth surface.
- It can be used to generate electricity or to heat buildings.
- Geothermal power is very reliable because the rocks are always hot.
- Most geothermal power stations only have a small impact on the environment.
Describe the effects of hydro-electric power on the environment and how they work.
- Hydro-electric power usually involves building a big dam across a valley
- The valley is usually flooded
- Water is allowed to flow out through turbines, which generates electricity.
- There is no pollution when it’s running
- But there’s a big impact on the environment due to the flooding of the valley
- Plants rot and release greenhouse gases which lead to global warming.
- There’s no problem with reliability in countries that get rain regularly.
- And it can respond straight away when there’s extra demand.
Describe how wave power effects the environment and how it it works.
- Turbines around the coast are turned by water waves and electricity is generated.
- There is no pollution
- But they disturb seabed and the habitats of animals
- They are fairly unreliable , as waves tend to die down when wind drops
Describe how tidal barrage effect the environment and how it works.
- Tidal barrage are big dams (with turbines in them ) built across rivers.
- Water passing through the turbines generates electricity.
- The amount of energy generated changes the tides
- But tidal barrages are very reliable, as we can predict the tires (we know what they are going to do)
- There is no pollution.
- But they do change the habitat of wildlife
- And often fish are killed as they swim through turbines.
What are bio fuels created from?
Plant products or animal dung.
