Energy

• What does energy define in a system?

  Capacity to do work on an object
• What happens to kinetic energy when a system is in motion?

  It experiences a change in kinetic energy
• What type of energy does an object gain when lifted?

  Gravitational potential energy
• What energy is gained when a spring is stretched?

  Elastic potential energy
• What are examples of energy in motion?

  • Ball rolling and hitting a wall
  • Vehicle moving down a hill
  • Water flowing down a waterfall
  • Bullet being fired
  • Atoms vibrating and transferring heat
• What is the formula for kinetic energy?

  Ek = ½mv²
• What does 'm' represent in the kinetic energy formula?

  Mass in kilograms
• What does 'v' represent in the kinetic energy formula?

  Speed in metres per second
• What is the formula for elastic potential energy?


  Ee = ½ks²
• What does 'k' represent in the elastic potential energy formula?

  Spring constant in N/m
• What does 's' represent in the elastic potential energy formula?

  Extension in metres
• What is the formula for gravitational potential energy?

  Ep = mgh
• What does 'g' represent in the gravitational potential energy formula?

  Gravitational field strength in N/kg
• What does 'h' represent in the gravitational potential energy formula?

  Height in metres
• What is the formula for calculating thermal energy change?

  Q = mcΔT
• What does 'c' represent in the thermal energy change formula?

  Specific heat capacity in J/kg°C
• What does 'ΔT' represent in the thermal energy change formula?

  Temperature change in degrees Celsius
• How is power defined in physics?

  Rate at which energy is transferred
• What is the formula for power?

  P = E/t
• What happens to power if work is done in less than one second?

  Power is greater than one watt
• What are the methods to reduce energy waste?

  • Lubrication (e.g., oil in a motor)
  • Thermal insulation (e.g., double glazing)
• What does thermal conductivity indicate about a material?

  How readily heat is transferred through it
• How does thermal conductivity affect energy transfer in buildings?

  • Higher thermal conductivity = faster heat transfer
  • Lower thermal conductivity = slower heat transfer
• What is the formula for efficiency?

  Efficiency = useful output / total input
• How can efficiency be increased in a system?

  • Reducing waste energy output
  • Recycling waste energy output
• What are the main non-renewable energy sources?

  • Fossil fuels (oil, gas, coal)
  • Nuclear fuel
• What are the main renewable energy sources?

  • Wind
  • Solar
  • Hydro
  • Geothermal
  • Tidal
  • Wave
  • Biomass
  • Hydrogen
  • Water waves
• How does renewable energy differ from non-renewable energy?

  Renewable can be replenished; non-renewable cannot
• Why have renewable energies become more important?

  Finite fossil fuels and environmental concerns
• What is a limitation of solar energy?

  It doesn't work at night or on cloudy days
• What is a limitation of wind energy?

  It isn't always available during night or bad weather
• What are the main uses of energy?

  • Transport
  • Electricity generation
  • Heating
• How did the industrial revolution affect energy sources?

  Fossil fuels became important and accessible
• Why has society moved towards renewable energy?

  To solve environmental problems and meet demands