Conservation of energy

• What is the formula for calculating the change in gravitational potential energy (GPE)?


  ∆GPE = mg∆h
• What does the equation ∆GPE = mg∆h represent?

  It calculates the change in gravitational potential energy as an object moves between heights.
• What units are used for mass, gravitational field strength, and change in vertical height in the GPE equation?

  Mass is in kilograms (kg), gravitational field strength in newtons per kilogram (N/kg), and height in metres (m).
• What is the formula for kinetic energy (KE)?

  KE = \frac{1}{2} mv^2
• What does the kinetic energy equation KE = \frac{1}{2} mv^2 calculate?

  It calculates the energy associated with a moving object.
• What do energy transfer diagrams illustrate?

  • Energy input and output
  • Forms of energy involved
  • Waste output energy
  • Energy wasted as heat in motors
• What happens to kinetic energy (KE) when an object is projected upwards?

  • KE is transferred to gravitational potential energy (GPE)
  • GPE is converted back to KE as the object falls
• What occurs when an object is projected up a slope?

  • KE is transferred to GPE
  • Some energy may be converted to heat if friction is present
• What happens when a moving object hits an obstacle?

  • KE is transferred to sound
  • KE may also be transferred to the obstacle if it moves
• What occurs when an object is accelerated by a constant force?

  • Work is done on the object
  • The object gains kinetic energy (KE)
  • Energy is transferred from the force supplier to KE
• What happens to kinetic energy (KE) when a vehicle slows down?

  • KE is transferred to heat through the brakes
• How is electrical energy transformed when boiling water in a kettle?

  • Electrical energy is converted to thermal energy
• What does the conservation of energy principle state?

  The total energy of an isolated system remains constant.
• What is a 'closed system' in physics?

  A closed system has no external forces acting on it.
• What happens to total energy in a closed system?

  The total energy never changes, regardless of energy transfers.
• What occurs when a system becomes an open system?

  Energy can be transferred out of the system, changing the total energy.
• What is mechanical waste energy?

  • Energy transferred to an object can cause a rise in temperature
  • Energy is dissipated to surroundings, making the process wasteful
• What are common forms of waste energy?

  • Light
  • Sound
  • Heat (most commonly)
• How can waste energy be reduced?

  • Lubricate systems to reduce friction
  • Use thermal insulation to minimize heat loss
• How do thicker walls in buildings affect thermal insulation?

  • Thicker walls provide greater thermal insulation, reducing heat loss
• What is the effect of air cavities between walls on heat loss?

  • Air cavities cause significant heat loss by convection
  • Cavity wall insulation prevents airflow and reduces heat loss
• How is efficiency defined in energy transfer?

  Efficiency is the ratio of useful output over total input of energy.
• How can efficiency be calculated?

  Efficiency = \frac{\text{useful energy transferred by the device}}{\text{total energy supplied to the device}}
• How can efficiency be increased?

  • Reducing waste output (via lubrication/thermal insulation)
  • Recycling waste output as input
  • Suitable methods depend on each situation
• What are some examples of energy sources?

  • Fossil Fuels
  • Nuclear Fuel
  • Bio-Fuel
  • Wind
  • Hydro-electricity
  • Tidal
  • Solar
• Why are non-renewable energy sources used more for large-scale energy supplies?

  • They provide a large energy output per kilogram of fuel
  • Renewable resources cannot provide such large amounts of energy as easily
• Why has renewable energy become more important recently?

  • Due to the finite lifetime of fossil fuels
  • Development of renewable energy sources has become crucial
• What was the significance of fossil fuels during the industrial revolution?

  • Fossil fuels became an important energy source due to ease of mining and high energy output
• What has changed regarding renewable energy since the industrial revolution?

  • Renewable energy has become more suitable due to technological advancements
• What is a closed system in terms of energy transfer?

  A closed system experiences no net change in its total energy when energy transfers occur within it.
• What does the law of conservation of energy state?

  The law states that energy can be transferred, stored, or dissipated but never created or destroyed.
• How is efficiency defined in energy transfer?

  Efficiency is the ratio of useful output energy transfer to total energy input.
• Why can efficiency never exceed 1 (or 100%)?

  Efficiency can never exceed 1 due to the conservation of energy.
• What are fossil fuels?

  Fossil fuels include coal, oil, and gas.
• What is gravitational potential energy?


  Gravitational potential energy is the store of energy that all raised matter has, proportional to mass, height, and gravitational field strength.
• What is the unit used for energy?

  The unit used for energy is the Joule.
• How is kinetic energy defined?

  Kinetic energy is the store of energy that all moving matter has, proportional to mass and the square of velocity.
• What is lubrication and its purpose?

  Lubrication is the application of a lubricant to reduce friction between surfaces, improving system efficiency.
• What is a non-renewable energy resource?

  A non-renewable energy resource is one that cannot be replenished while it is being used and is finite.
• What is a renewable energy resource?

  A renewable energy resource is one that can be replenished while it is being used.