everything

• A scalar quantity is just a number
• A vector quantity is a number and a direction
• Scalar quantities


  • Distance
  • Mass
  • Speed
• Distance


  Measured in meters
• Speed/Velocity


  Measured in meters per second
• Time


  Measured in seconds
• Interpreting distance-time graphs


  1. Increasing slope = moving faster

  2. Flat line = not moving

  3. Gradient = speed
• Interpreting velocity-time graphs


  1. Flat line = moving at steady speed

  2. Increasing slope = accelerating

  3. Gradient = acceleration

  4. Area under graph = distance
• Gravity on Earth


  10 Newtons per kilogram
• Acceleration due to gravity on Earth

  10 meters per second squared
• Finding resultant force


  Difference between forces
• Weight


  Mass x gravity
• Centripetal force


  Resultant force when moving in a circle
• Law of conservation of momentum: momentum before = momentum after
• Stopping distance


  Thinking distance + braking distance
• Factors affecting thinking distance: alcohol, drugs, tiredness
• Factors affecting braking distance: tire condition, road condition, car weight</b>
• Types of energy


  • Gravitational potential
  • Electrical
  • Elastic potential
  • Kinetic
  • Sound
  • Light
  • Nuclear
  • Chemical
  • Thermal
• Law of conservation of energy: energy cannot be created or destroyed, only transformed
• Wasted energy


  Energy that comes out but wasn't intended, e.g. heat and sound from a light bulb
• Dissipation of energy


  Wasted energy spreading out so much it can't be collected and used
• Sankey diagram


  Visual representation of energy efficiency, with useful energy and wasted energy shown
• Infrared cameras can detect heat loss from buildings
• New buildings are more energy efficient, old buildings can be adapted to be more efficient</b>
• Renewable energy sources


  • Sun
  • Wind
  • Water (tidal, hydroelectric, wave)
  • Geothermal
• Non-renewable energy sources


  • Fossil fuels (coal, oil, gas)
  • Nuclear
• Advantages of renewable energy

  • Don't release CO2
  • Inexhaustible
  • Non-polluting
• Disadvantages of renewable energy

  • Intermittent (e.g. no sun at night)
  • Can be expensive to install
  • Can disrupt local environment
• Advantages of non-renewable energy

  • Readily available
  • Cheap
• Types of resources


  • Finite resources (fossil fuels, nuclear power)
  • Renewable resources (solar, wind, tidal, wave, geothermal)
• Advantages of renewable resources

  • Don't release carbon dioxide
  • Inexhaustible
  • Generally non-polluting
• Disadvantages of solar power

  • Doesn't work at night
  • Not very good on cloudy/wintry days
  • Can be expensive to install
• Disadvantages of wind turbines

  • Some people don't like them
  • Don't work well on non-windy days
• Disadvantages of tidal/wave power

  • Can be disruptive to local environment
• Disadvantage of hydroelectric dams

  • Involves flooding large areas, including people's homes and animal habitats
• Disadvantage of geothermal power

  • Can only be used in volcanic countries
• Advantages of fossil fuels/nuclear power

  • Very readily available
  • Very cheap source of electricity
  • Short start-up time
• Disadvantages of fossil fuels

  • Take millions of years to create, so we're about to run out
  • Very heavily polluting, release large amounts of carbon dioxide and other pollutants
• Disadvantage of nuclear power

  • Have to store radioactive waste for long periods
  • Small but potential risk of explosion
• Longitudinal wave


  Areas of compression and refraction, wavelength measured from one point to another, direction of movement and energy is side to side