Physics paper 1

• Main energy resources on Earth

  • Fossil fuels (coal, oil, gas)
  • Nuclear fuel
  • Bio-fuel
  • Wind
  • Hydroelectricity
  • Geothermal
  • Tides
  • Sun
  • Water waves
• Renewable energy resources


  Will never run out
• Non-renewable energy resources


  Will run out in the future
• Renewable energy


  • Can be 'renewed' as it's used
  • Can do damage to environment but less than non-renewable
• Non-renewable energy


  • Fossil fuels and nuclear fuels (uranium & plutonium)
  • Form underground for millions of years
  • Don't provide much energy/enough damages the environment
  • Some are unreliable as depend on weather
  • Reliable energy resources
• Coal, oil and gas are the main fossil fuels and non-renewable energy
• Energy is never created nor destroyed only ever transferred between different forms and objects
• System


  A collection of matter
• Open system


  Can lose or gain energy - as it interacts with outside world
• Closed system


  Matter and energy cannot enter or leave (overall change always zero)
• Work done


  Energy transferred
• Types of work done

  • Mechanical
  • Electrical
• Mechanical work


  Using a force to move an object
• Electrical work


  When current flows (energy required to overcome the resistance in the wires)
• Energy can be transferred usefully, stored or dissipated but can't be created or destroyed
• Lubrication reduces frictional forces
• Insulation reduces the rate of heat energy transfer
• Efficiency

  Useful power output / Total power input
• Particle


  A small sphere that makes up all matter around us
• States of matter


  • Solid
  • Liquid
  • Gas
• Changes of state


  • Melting
  • Boiling
  • Freezing
  • Condensing
• Kinetic energy


  The energy stored in a moving object
• Motion of particles in a gas

  • Fast, random motion
• One way we can understand the world around us is to assume the are made from particles
• We model particles as tiny spheres that can be arranged in different ways to give different substances different properties
• The different arrangements we call the states of matter
• Particle diagram rules for solids


  • All particles must touch
  • The particles are ordered
• Particle diagram rules for liquids


  • The particles must touch
  • The particles are random
• Particle diagram rules for gases

  • The particles are spread apart
  • The particles are random
• Properties of solids


  • Keep their shape
  • Are incompressible
  • The particles vibrate in place
• Properties of liquids


  • Can flow
  • Are incompressible
  • The particles can move over each other
• Properties of gases


  • Can flow
  • Are incompressible
  • The particles travel at high speeds
• Changes of state


  1. Adding energy to a solid gives the particles the ability to move over each other, becoming a liquid

  2. What must happen for the state to turn to a gas?
• Names of changes of state

  • Melting
  • Boiling
  • Condensing
  • Freezing
• Explaining changes of state

  1. Particles start to vibrate faster and then move away from their fixed places, causing a random arrangement of the particles, but the particles are still touching

  2. Particles start to move faster and then move away from each other, causing the particles to spread apart and move randomly in the space
• Density is a number that describes how much mass there is in a set volume of substance
• If two blocks have equal volumes, but one is made of plastic and one is made of metal


  The metal block will be heavier, and therefore have a higher density
• Objects with a higher density than water sink
• How particle model shows density

  More particles is more mass, more mass in the same space means a higher density
• Density equation


  Density = Mass / Volume