topic 1

• what energy transfers occur when: an archer pulls back a bow, an archer releases a bow

  as an archer pulls back a bow, chemical energy from the muscles is transferred mechanically to elastic potential energy of the string. when the archer releases the bow, the elastic potential energy is transferred mechanically to kinetic energy.
• what makes conduction and convection similar and different?

  Conduction and convection both involve particles gaining kinetic energy, however in conduction particles physically touch, while in convection there is an energy transfer through the fluid
• what is weight?

  weight is the force due to the pull of gravity of an object.
• what is thermal conductivity? what types of material have a high and low thermal conductivity?

  How well objects transfer energy through conduction is known as their “thermal conductivity”. Metals are found to have high thermal conductivity, and fluids and plastics have low ones (plastics are insulators)
• What is the principle of the conservation of mass?

  Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
• what is the law of conservation of energy?

  energy cannot be created or destroyed, only transferred between energy stores
• what is the equation that links weight, mass and gravitational field strength?

  weight (N) = mass(kg) x gravitational field strength (N/kg)
• what is the equation that links kinetic energy, mass and velocity?

  Ek = 1/2mv2
• what is the equation that links change in internal energy, mass, SHC and temperature change?

  change in internal energy (J) = mass (kg) x SHC (J/kg degree celsius) x temp change (degree celsius)
• what is the equation that links gravitational potential store, mass, gravitational field strength and height?

  Ep (J) = Mass (kg) x gravitational field strength (N/kg) x height (m)
• what is the equation for efficiency?

  Efficiency = useful energy output / total energy output
• what is specific heat capacity?

  the amount of energy needed to heat up 1kg of a substance by 1 degree celsius
• what is radiation? what do all objects emit and absorb?

  Heat energy can be transferred without particles - radiation. Heat is transferred via infrared waves. All objects emit radiation and absorb it - the hotter an object, the more radiation there is absorbed and emitted.
• what is mass?

  mass is the measurement of the quantity of matter in an object
• what is lubrication and what is it used for (give an example)?

  lubrication reduces the amount of efficient energy used, for example in bicycles. To reduce friction, we add lubricants such as oil to the pedals which makes it easier to pedal
• what is kinetic energy?

  the energy that something possesses due to its motion.
• what is internal energy?

  the total energy stored by the particles making up a substance (potential energy + kinetic energy)
• what is gravity?

  gravity is a force of attraction between 2 objects. 
• what is efficiency?

  Efficiency is the proportion of energy supplied to a useful energy output (doesn’t necessarily have to be energy, can be power)
• what is convection, give examples and how can we prevent it?

  Convection occurs when heat energy transfers to the fluid particles. The particles closer to the heat source rise up (become less dense), and the cooler ones sink down towards the heat. The cooler particles now heat up, and the warmer ones cool down, repeating a cycle - a convection current. This occurs in oceans and radiators. To reduce convection, we need to stop the free flow of fluids.
• what is conduction and how does it work?

  The key idea of conduction is that the heat energy transfers to the kinetic energy store of the particles and they start vibrating faster, passing on their kinetic energy to neighbouring particles. This continues until heat is spread evenly.
• What is an open system?

  An open system is a system where energy and matter in the system can freely move to the environment, for example a phone.
• What is a system?

  Systems are a portion of the physical universe that is being analysed, and the environment is everything outside that system.
• What is a closed system?


  A closed system is the opposite - energy and matter cannot freely move, for example a phone in a sealed jar. 
• What happens to the overall energy of an open and closed system?

  in an open system, the overall energy can change. in a closed system, it cannot.
• what happens to the kinetic and gravitational potential stores as an object moves up?


  kinetic energy decreases and gpe increases, because kinetic energy is being converted to gpe. the highest point of an object is where the most gravitational potential energy is stored and it is also where the minimum amount of kinetic energy is stored
• what happens to the kinetic and gravitational potential energy stores as an object falls?


  kinetic energy increases and gpe decreases, because gpe is being converted back to kinetic energy. Therefore when the ball is moving at its highest speed is where the maximum amount of kinetic energy is stored - meaning the minimum gpe is stored there as well
• what happens to temperature as internal energy increases?


  temperature increases as the particles move faster due to higher kinetic energy
• what does the gravitational potential energy store, store?

  the energy required to overcome a force of gravity
• what does "work done" mean?

  Work done is used when force is used to move an object at a certain distance
• what are wave machines? 

  Water in the sea rises and falls due to waves. Wave machines use the kinetic energy in this movement to drive electricity generators
• what are tidal barrages?

  Tidal barrages also trap water using tides. As there are high tides, water flows into a bay and is trapped. The water is then released during a low tide
• what are the ways heat can take place, and in what types of matter?

  • The process of heating can take place in 3 different ways:
  • In solids, through conduction
  • In fluids, through convection (this includes liquid and gas)
  • In a vacuum, through radiation
• what are the two definitions of power and their corresponding equations?

  • The rate at which energy is transferred 

                                                    (P = E/t)

  • The rate at which work is done

                                                    (P = W/t)
• what are the pros and cons of wave machines?

  • Renewable energy source
  • No harmful polluting gases
  • Difficult to scale up designs for wave machines to produce large amounts of electricity
  • Having wave machines can negatively affect wildlife
• what are the pros and cons of hydroelectric dams and tidal barrages?


  • Can produce lots of energy with no pollution
  • Reliable sources of electricity
  • Running costs ar below
  • Works on small and large scales
  • Can have a big impact on the environment, especially hydroelectric dams, e.g. floods land upstream
  • Initial setup is expensive
• what are the pros and cons of biofuels?

  • Renewable
  • Cheap to make
  • Easy to transport
  • You can mix them with fossil fuels, so we can benefit from them without getting new cars
  • Needs somewhere to grow all the plants, which can involve cutting down forests, which releases CO2
  • We need to harvest, process and transport these plants, which requires energy itself
• what are the methods of energy transfer?

  • mechanically
  • electrically
  • heating
  • infrared radiation
  • light waves
  • sound waves
• what are the 8 energy stores?

  • thermal
  • gravitational potential
  • elastic
  • magnetic
  • chemical
  • electrostatic
  • nuclear
  • kinetic
• what are the 2 factors that influence the size of gravity?

  the mass of the objects and the distance between the objects