Physics P2

• The SI unit of energy is the joule (J)
• Potential Energy - stored energy due to an object's position, shape or condition
• Kinetic Energy - The energy an object has due to its motion, measured in Joules.
• Kinetic Energy - energy possessed by moving objects as they move
• Work Done = Force x distance moved in direction of force
• Work done = force x distance moved in direction of force
• Power = work done / time taken
• Energy efficiency = useful output energy / total input energy
• Energy Transfer - transferring energy from one form to another
• Conservation of Energy - the total amount of energy remains constant during any process, it is neither created nor destroyed.
• Current (I) = amount of charge passing through a point per second
• Specific Heat Capacity - the amount of heat required to raise the temperature of 1 kg of substance by 1 degree Celsius
• Kinetic Energy (KE) - energy due to motion
• Elastic Potential Energy - energy stored when an object is stretched or compressed
• Resistance (R) = opposition to current flow
• Thermal Conductivity - how well a material conducts thermal energy
• If a small bucket and large bucket of water was left in the sun which would heat up faster?

  the smaller one because their is a smaller volume to heat up and the ratio of volume to SA is greater than the large bucket
• why are plastic frames better than metal frames in windows

  Because they are better insulators and they do not corrode as easily
• why is it better to wear a white hat than a black hat in the sun

  because white reflects the light preventing sunburn etc whereas black absorbs the sun.
• Efficiency


  The ability to perform a task with minimum waste of effort
• Ways to increase efficiency

  • Thermal insulation
  • Lubrication
  • Streamlining
• 100% efficiency is usually impossible
• There is usually always some wasted heat energy in the form of heat / thermal energy
• Sometimes the definition of 'useful' energy can change - e.g. some lights are designed to provide heat and light, so the heat energy is also useful
• Ways to reduce unwanted energy transfers

  • Thermal insulation
  • Lubrication
  • Streamlining
• Thermal insulation


  Reducing thermal energy transfer through windows, doors and walls
• Lubrication


  Reducing energy loss due to friction
• Streamlining


  Reducing air resistance on objects travelling through the air
• Cooling a building


  1. Use double glazed windows

  2. Use insulated walls

  3. Use loft insulation
• Thermal conductivity decreases as thickness increases
• Double glazed windows


  Using double glazing thickens the windows and reduces their thermal conductivity, decreasing the rate of thermal energy transfer
• Insulated walls


  Walls can have high thermal conductivity, allowing lots of thermal energy transfer. Adding an air gap or filling it with foam increases the thickness and decreases the thermal conductivity
• Loft insulation


  Lofts can transfer a lot of thermal energy via thermal conductivity. Lining them with fibreglass wool insulates the loft and prevents energy losses
• Energy waste refers to the loss of energy that occurs during the production, distribution, and use of electricity, gas, and other forms of energy
• Reducing energy waste is important

  It can save money, reduce carbon emissions, and conserve natural resources
• Simple ways to reduce energy waste

  • Turning off lights and appliances when not in use
  • Using energy-efficient light bulbs
  • Insulating your home
  • Using a smart thermostat
  • Setting computer to "sleep" mode
  • Unplugging chargers and electronics when not in use
• Ways to reduce energy waste in your home

  • Installing low-flow showerheads and toilets
  • Replacing old appliances with energy-efficient models
  • Sealing air leaks around windows and doors
  • Planting trees
  • Insulating your attic, walls, and floor
• Impact of energy waste on the environment

  Energy waste contributes to greenhouse gas emissions and can lead to air/water pollution, habitat destruction, and other environmental problems
• How schools and communities can reduce energy waste

  • Installing energy-efficient lighting and appliances
  • Encouraging use of public transportation, biking, or walking
  • Recycling and composting
  • Implementing an energy management program
  • Hosting educational programs and events
• Hooke's law


  The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded