P1 energy resources and transfers

• How many main stores of energy are there?

  8 main stores of energy
• What are four of the main energy stores?

  • Chemical
  • Kinetic
  • Gravitational
  • Elastic
• What does "conservation of energy" mean?

  Energy cannot be created or destroyed
• What happens to energy in a closed system according to conservation of energy?

  The total amount of energy remains constant
• What are the four main transfer types between energy stores?

  Mechanically, electrically, by heating, by radiation
• How is energy transferred through electrical equipment?

  Current converts chemical energy into other forms
• How does work done by forces change energy?

  A force converts energy mechanically by work done
• What energy changes occur when a skateboarder goes down a hill?

  GPE converts to KE and friction energy
• What happens to energy when a skateboarder comes to rest at the bottom of a hill?

  All energy is lost as heat through friction
• What equation is used to calculate the efficiency of a system?

  Efficiency = useful energy output / total energy input

  
• What energy changes occur when a moving car stops?

  Kinetic energy changes to heat and sound energy
• What energy changes occur when a ball rolls down a hill?

  GPE turns into KE as it rolls down
• What is wasted energy?

  Energy not used for its intended purpose
• How can thermal energy be transferred?

  Conduction, convection, and radiation
• Why is the electrical heater of a kettle placed at the bottom?

  Heat transfers mainly by convection in fluids

  
• How does the thickness of a building's walls affect cooling rate?

  Thicker walls decrease the rate of cooling
• What happens to heat when building walls are thicker?

  Heat has to travel further to escape
• What is the main method of heat transfer in fluids?

  Convection
• What happens to a heated part of a liquid?

  It expands and becomes less dense
• What occurs to the colder part of the liquid when heated liquid rises?

  It sinks down within the liquid
• What forms when a heater is placed at the bottom of a liquid?

  A convection current
• How does the thickness of a building's walls affect cooling?

  Thicker walls decrease the rate of cooling
• How does thermal conductivity affect the rate of cooling?

  Higher conductivity increases the rate of cooling
• What materials have high thermal conductivity?

  Metals
• What material has lower thermal conductivity?

  Air
• How do surfaces affect heat transfer by radiation?

  Hot objects emit, cold objects absorb radiation
• What type of surfaces are good emitters/absorbers of thermal radiation?

  Black, dull surfaces
• What type of surfaces are good reflectors of thermal radiation?

  White, shiny surfaces
• How can you reduce unwanted heat transfer?

  • Insulation in walls and ceilings
  • Double glazed windows
  • Curtains to prevent heat loss
• What equation measures work done on an object?

  Work Done = Energy Transferred

  
• What is the relationship between work done and energy transferred?

  They are equal
• What is the equation for change in gravitational potential energy?

  ∆GPE = m x g x ∆h
• What does ∆GPE represent?

  Change in gravitational potential energy
• What is the equation for kinetic energy?

  KE = ½mv²
• What does kinetic energy depend on?

  Mass and speed of the object
• What does "power" mean in physics?

  • Rate at which energy is transferred
  • Work done per unit of time

  
• What equation links work done, power, and time taken?

  Power = Work Done / Time

  
• What is another way of describing a watt?

  1 Watt = 1 joule per second