Physics - Topic 3 - Conservation of Energy

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

  ∆𝐺𝑃𝐸 = 𝑚𝑔xℎ
• What does the equation for change in GPE represent?

  It calculates the change in GPE as an object is moved from one height to another.
• What are the units 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 meters (m).
• What is the formula for kinetic energy (KE)?

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

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

  • Energy input and output
  • Forms of energy taken
  • Waste output energy
  • Heat waste from 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 convert to heat due to friction
• What happens when a moving object hits an obstacle?

  • KE is transferred to sound energy
  • 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 common)
• 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 energy efficiency?

  • Thicker walls provide greater thermal insulation
  • Less heat is lost to surroundings
• What is cavity wall insulation?

  • Fills air cavities between walls
  • Prevents heat loss by convection
• What is the formula for efficiency?

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

  • Reduce waste output (via lubrication/thermal insulation)
  • Recycle waste output as input
  • Methods depend on the situation
• What are some sources of energy?

  • 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 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 trend occurred during the industrial revolution regarding energy sources?

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

  • Technology has developed to harness renewable energy sources efficiently