Energy
- Created by: Abc312
- Created on: 15-05-18 19:56
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- Energy
- A system is an object or group of object.
- There are changes in the way energy is stored when a system changes
- The energy stores are:
- Thermal
- Kinetic
- Gravitational Potential
- Elastic Potential
- Chemical
- Magnetic
- Electrostatic
- Nuclear
- Energy can be transferred by:
- Heating
- Work done by forces
- Work done when a current flows
- Kinetic energy
- =
- 0.5
- x
- mass
- x
- speed^2
- m/s
- speed^2
- kg
- x
- mass
- x
- 0.5
- Joules
- =
- Elastic potential energy
- =
- 0.5
- x
- spring constant
- x
- extension^2
- meters
- extension^2
- N/m
- x
- spring constant
- x
- 0.5
- Only if the limit of proportionality has not been exceeded
- Joules
- =
- Gravitational potential energy
- =
- mass
- x
- gravitational field strength
- x
- height
- meters
- height
- N/kg
- Always given in question
- x
- gravitational field strength
- kg
- x
- mass
- Joules
- =
- Change in thermal energy
- =
- mass
- x
- specific heat capacity
- x
- temperature change
- °C
- temperature change
- Joules per kilogram per degree Celsius (J/kg °C)
- This is the amountof energy neededto raise the temperature of 1kg of a substance by one °C
- x
- specific heat capacity
- kg
- x
- mass
- Joules
- =
- For a falling object with no air resistance
- Energy lost in gravitational energy store
- =
- Energy gained in the kinetic energy store
- =
- Energy lost in gravitational energy store
- Power
- =
- energy transferred
- ÷
- time
- seconds
- time
- Joules
- ÷
- energy transferred
- Watts
- One joule of energy per second= one watt
- =
- Work done
- ÷
- time
- seconds
- time
- Joules
- ÷
- Work done
- This is the rate of energy transferor doing work
- =
- Conservation of energy
- Energy is never created or destroyed only transferred usefully, stored or dissipated
- A closed system shows no energy change
- Dissipated energy is sometimes called wasted energy
- Because some energy is stored in a way that is not useful.
- Reducing unwanted energy transfers
- Lubrication
- Reduces frictional forces
- Insulation
- Prevents energy loss so they don't lose heat
- The higher the thermal conductivity transfer heat quicker
- Lubrication
- Conduction and Convection
- Conduction is where vibrating particles transfer energy to neighbouring particles
- This mainly happens in solids
- Convection is where energetic particles move from hotter to colder regions
- This is in gases and liquids
- Warmer air is less dense so rises above the cooler air
- This means a convection current is created if there is a constant heat source
- Conduction is where vibrating particles transfer energy to neighbouring particles
- Energy sources
- Renewable energy is one that can be replenished as it is used
- Sun/solar
- Often used in items that don't use much electricity
- No pollution
- Are reliable in sunny countries but only in the daytime
- Cannot increase the power output to demand
- Initial costs high and minimal running costs
- Wind
- No pollution
- Cannot increase supply with demand
- Cover a lot of ground
- Initial costs high, minimalrunningcosts
- Waves
- Lots of wave powered turbines are needed
- No pollution
- Unreliable as the waves drop when wind drops
- Destroys habitat and can be a hazard to boats
- Initial high costs but minimal running costs
- Hydro-elecricity
- A dam is filled and water is allowedthroughturbines
- Big environmental impact
- The flooding of the valley causes rotting and loss of habitat
- Can provide a response to an increased demand
- Initial costs high but minimalrunningcosts
- Bio-fuel
- Made from plants and waste
- Cannot react instantly to a bigger demand
- Cost to refine bio-fuels is very high
- Decay and burning of materials increases Co2 and methane emissions
- Tides
- Dams are built across river estuaries and water is allowed through turbines at a controlled rate
- No pollution but reduces boat access and destroys habitats
- Relaiable -happentwice a day without fail
- Hard to find a suitable place
- Initial costs high and running costs low
- Geothermal
- Used in volcanic areas with hot rocks near the surface
- Does little environmental damage
- Usually from decay of radioactive elements
- High cost
- Not many suitable places
- Sun/solar
- Non-renewable means we will run out of it
- Our three main fossil fuels are
- Coal
- Oil
- Natural Gas
- They are reliable as there are enough to meet current demand
- We are able to use them to respond quickly to changes in demand
- They are slowly running out
- If we continue using them at this rate they could run out within 100 years if we find no more
- Power plants can cost a lot to set up
- the running costs are not that expensive
- They all relate CO2 into the atmosphere
- They release sulfur dioxide causing acid rain
- Coal mining ruins the landscape
- Nuclear waste is hard to get rid of
- Also carries the risk of a catastrophe
- Oil spillages can damage the environment
- Our three main fossil fuels are
- Renewable energy is one that can be replenished as it is used
- A system is an object or group of object.
- Change in thermal energy
- =
- mass
- x
- specific heat capacity
- x
- temperature change
- °C
- temperature change
- Joules per kilogram per degree Celsius (J/kg °C)
- This is the amountof energy neededto raise the temperature of 1kg of a substance by one °C
- x
- specific heat capacity
- kg
- x
- mass
- Joules
- =
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