physics

avatar
Created by
inas khelfaoui

Cards (274)

  • Kinetic Energy

    The energy stored in moving objects. Stationary objects have no kinetic energy.
  • Ek =

    0.5 x m x v2
  • Elastic potential energy

    The energy stored in a spring when work is done to it (stretching)
  • Ee =

    0.5 x k x e2
  • Gravitational Potential energy

    The energy stored in an object due to its position above the earths surface. This is due to the force of gravity acting on an object.
  • Specific heat capacity

    The amount of energy required to raise the temperature of 1K of the substance by 1 degree
  • Change in Energy =
    mass x specific heat capacity x temperature cahnge
  • Practical: Specific heat capacity
    1. Record mass of vegetable oil in a beaker
    2. Place a thermometer and an immersion heater into the oil
    3. Read the starting temperature
    4. wrap the beaker in insulating foam
    5. Connect a joule meter and a power pack
    6. Time for thirty minuets
    7. Read the total number of joules and the final temperature
  • (Closed) System

    A system is an object or a group of objects. In a closed system no energy can enter or leave. It is conserved.
  • Energy Transfers

    We can reduce unwanted energy transfers by:
    -Using a lubricant
    -Removing air particles
  • Work Done

    Whenever energy is transferred from one store to another work is done
  • Work done =

    force x distance
  • Power

    The rate at which energy is transferred or the rate at which work is done
  • power =

    Energy transferred / time
  • power =

    work done / time
  • Efficiency =

    Useful output energy transfer / total input energy transfer
  • Efficiency =

    useful power output / total power input
  • Improving Efficiency

    - Builders prevent thermal energy from escaping by packing walls with low thermal conductivity materials
    - Double glazed windows
    - Loft insulation
    - Houses with thick walls
  • Energy Uses

    - Transport
    - Generating Electricity
    - Heating
  • Fossil Fuels

    Coal gas and oil:
    + Very Reliable
    + Release lots of energy
    + Abundant a relatively cheap
    + Versitile
    - Releases carbon dioxide
    - Non-renewable
    - Release pollutants (sulfur dioxide causes acid rain)
  • Nuclear power

    + Release no Carbon dioxide
    + reliable
    - non renewable
    - highly dangerous
    - decommissioning nuclear is expensive
    - radioactive waste must be stored
  • Renewable

    A source that is being replenished at the smae or a faster rate than it is being used
  • Wind Power

    + never run out
    + no CO2
    - unreliable
    - not portable
  • Solar power

    + never run out
    + no CO2
    - unreliable
    - not portable
  • Hydroelectric power

    + never run out
    + no CO2
    + reliable
    - destroys habitats
    - floods valleys
    - not portable
  • Tidal Power

    + never run out
    + no CO2
    + reliable
    - harmful to wildlife
    - not portable
  • Geothermal

    + never run out
    + no CO2
    + reliable
    - not portable
  • Wave power

    + never run out
    + no CO2
    + reliable
    - small scale
    - not portable
  • Biofuel

    + never run out
    + no CO2
    + carbon neutral
    - increase food price
  • Electric current

    The current flows from the negative end of the cell to the positive end of the cell. The electrons are carrying the energy, they pass it to the components.
  • Current (A)

    Measured in amperes on an ammeter.Never used up.
    In series current is always the same, in parallel, the current in each branch adds to the current in the cell.
  • current =

    charge / time
  • charge =

    energy transferred / time
  • Potential Difference (V)

    The amount of energy transferred for each coulomb of charge that is moving through a circuit.
    measured in volts with a volt meter.
    In series, v is split. In parallel, V is the same
  • Battery

    the potential difference of the cells adds up to tell us the potential difference of a battery.
  • Resistance

    The potential difference required to drive a current through a component.
  • resistance =

    potential difference / current
  • Resistor

    The current is directly proportional to the potential difference (ohmic conductor) if temperature is constant.
    In series, add. In parallel, the total resistance is less than the resistance to the smallest reistor.
  • Filament Lamp

    More resistance as it gets hotter so not directly proportional.
  • Diode

    Current only flows one way due to high resistance the other way. They are useful for controlling the flow of a circuit.