Physics Topic 1 : Energy

• Formula of gravitational potential energy


  GPE = mgh
• Formula for elastic potential energy


  potential energy of a spring = 0.5 x spring constant x (extension)^2
• What is a closed system?

  A system where neither matter nor energy can enter or leave
• what is an open system?

  energy can be gained or lost and transferred
• when a ---- changes energy is ---

  when a system changes energy is transferred
• whats a system


  An object or group of objects
• Name all the energy stores

  Thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear
• Define conduction and give an example

  the process where vibrating particles transfer energy to neighbouring particples
• formula for power


  work/time
• formula for efficiency


  output work/input work x 100%
• formula for thermal energy


  q = mcΔT
• state the two formulas for power

  power+energy transferred/time

  power=workdone/time
• What is convection?


  heat transfer in a fluid in which hot fluid rises and cold fluid sinks, setting up a

  cycle
• Formula for work done

  Work done = force x distance
• What is work done?

  energy transferred from one state to another
• what is mechinal and electrical work done?

  mechinal work involves using a force to move an object

  electrical work invovles a current transferring energy
• pros and cons for solar energy

  pros:

  no pollution

  very reliable in sunny countries

  cons:

  can increase power output when there is extra demand

  relys on weather.
• pros and cons of wind turbines

  pros:

  no pollution

  no permanent damage

  cons:

  initial costs are high

  noisy

  unattractuve
• pros and cons of biofeuls

  pros

  Sustainable. Doesn't rely on fossil fuels. Can be made quickly. Carbon Neutral

  cons

  Not much energy in comparison to Fossil Fuels. Large amounts of land is needed to create this - destroying wildlife.
• advantages and disadvantages of nuclear power>?

  Advantages: Reliable, Powerful, can be done anywhere,

  
  

  Disadvantages: Dangerous, not renewable, waste is very radioactive, bad for environment
• State 7 renewable energy resources

  Wind, tidal, hydroelectric, wave, solar, geothermal, biomass
• what are the non renewable resources?

  coal, oil, natural gas, nuclear
• what does insulation reduce


  Rate at which energy is transferred to the surroundings
• what is internal/thermal energy?

  the total kinetic and potential energy of the particles in an object, in most cases this is the vibrations - also known as the kinetic energy - of most particles. In hotter objects, the particles have more internal energy and vibrate faster.
• What is the law of conservation of energy?

  Energy cannot be created or destroyed, only transferred
• define specific heat capacity

  it is the amount of energy needed to raise the temperature of 1 kg of a substance by 1 degrees celsius
• ignoring air resistance describe the changes in the way energy is stored that take place as an object falls

  As the object falls, its height above the ground decreases. Therefore, its gravitational potential energy decreases accordingly. The potential energy is transferred into kinetic energy as the object accelerates towards the ground.
• if air resistance was not ignored?


  air resistance acts against the falling objects causing some energy to be transferred to other stores
• what is conduction


  the process of heat transfer through a material or between materials due to the collision of particles (atoms or molecules) within the material
• what is convection


  heat transfer through the movement of fluid (liquids or gases).
• what is thermal conductivity


  A measure of how quickly energy is transferred through a material via conduction
• a material wtih high thermal conductivity will

  transfer energy between particles quickly
• whats lubrication


  redcues frictional forces
• pros of non-renewable resources

  reliable

  easy to extract
• cons of non-renewable


  will all 'run out' one day

  do damage to the enviroment
• what are renewable energy resources

  They are energy resources that will never run out, as they can be "renewed" as they are used.
• examples of renewable energy resources

  the sun

  wind

  water waves

  hydro-electricity

  bio-fuel

  tides

  geothermal
• what is natural gas (non renewable energy) used for

  a feul for heating homes, the gas is used to heat water,pumped into radiators throughout the home
• pros and cons for geothermal (energy from underground)

  cons:

  only possible in volcabic areas

  arent sutiable locations for power plants

  cost of building a powerplant is high compared to the amount of energy it produces

  pros:

  can heat buildings directly

  reliable
• pros and cons for hydroelectric power (uses falling water)

  pros:

  no pollution

  provide an immediate response to an increase in demand

  no feul costs and minimal running costs

  useful in reomte areas

  
  

  cons:

  big imapct on enviroment, loss of habitat

  initial costs are high