Physics P1

Cards (142)

  • What is efficiency?

    Useful power output/ total power input
  • specific heat capacity
    amount of energy needed to raise temp of 1kg of substance by 1 degrees
  • types of energy stores
    gravitation potential, thermal, kinetic, elastic potential, chemical, magnetic, electrostatic, nuclear
  • ways in which energy can be transferred
    mechanically (work done by a force), electrically (work done by moving charges) or by heating
  • what is a ‘system’
    Object or a group of objects
  • when object slows down, which store is loosing energy
    kinetic energy store
  • energy can be created but not destroyed

    false - conservation of energy principle states energy can never be created OR destroyed
  • what does energy transferred usefully mean

    transferred into the store you want it to go to
  • equation for power + work done
    power = work done/time
  • what does a ‘powerful’ machine mean

    a machine that can transfer a lot of energy in a short space of time
  • should thermal insulation have high or low thermal conductivity
    low thermal conductivity
  • what would an efficiency of 0% tell you

    device doesn’t transfer any energy usefully
  • main fossil fuels
    coal, oil + natural gas
  • renewable energy resources
    sun(solar), wind, water waves, hydro-electricity, biofuel, tides + geothermal
  • material that can be used to make biofuels
    plant products or animal dung
  • energy resource that only produces power during daytime
    solar power
  • what’s tidal energy used for

    to generate electricity
  • is wave power reliable
    no, waves tend to die out when the wind drops
  • why is electricity generated by mostly non-renewable energy resources
    generate electricity fairly cheaply using fossil fuels + supply is reliable
  • current in single closed loop of wire is the same at any point
    true
  • equation that links charge flow, current + time
    charge flow= current x time
  • equation that links potential difference, current + resistance
    potential = current x resistance
  • diode has a very high resistance in one direction
    true
  • relationship between pd and current for ohmic conductor at a constant temp
    Current is directly proportional to potential difference
  • thermistors can be used in thermostats that control the temperature of a room
    true - used in lots of devices that need to sense temperature change
  • all components in a series will have the same size current flowing through them

    true - current in series circuit is same at any point
  • how to find total resistance of a series circuit
    adding up resistance of each component in circuit
  • current through all components connected in parallel is always the same
    false - current shared between branches, pd across components are the same
  • Conservation of energy and power
    Energy can be transferred used, stored or dissipated but can never be created or destroyed
  • power
    rate of doing work (watts)
  • power
    power (w) = energy transferred (j) / time (s)
  • movement
    energy in an objects kinetic energy store
  • what does lubrication do

    reduces friction which can be dissipated, lubricants are liquids = flow easily between objects + coat them
  • what can heating occur by 

    convection and conduction
  • high thermal conductivity
    energy transferred at a faster rate, particles move faster
  • closed systems
    neither matter nor energy can enter or leave
  • boiling water in kettle
    Energy transferred to water by heating into waters thermal energy store
  • work done
    energy transferred, work can be done when current flows or by a force moving an object
  • initial force exerted on a person
    ball upwards = work done
    transfer from chemical store of arm to kinetic store of ball and arm
  • initial force exerted by a person
    ball from height = accelerated by gravity
    gravitational force does work
    energy transfer from balls gravitational potential store to kinetic store