Physics Unit 3: Winter Chills

Unit 3: Winter Chills

• This unit explores energy and its conservation
• Students will understand and calculate:
  • The Law of Conservation of Energy in various contexts
  • How to calculate energy conservation effectively
  • The difference between useful and consumed energy
  • Energy efficiency calculations
  • The difference between heat and temperature
• Textbook pages 70-74 cover the content
• 3.1 Prior Knowledge:
  • Energy is the amount of work an object can do or store
  • Work is the amount of force applied over a distance
  • The unit for energy is Joules (J)

Energy

• Energy can be potential or kinetic
  • Potential energy is the energy an object has at rest
  • Kinetic energy is the energy an object has as it moves
• Energy Transformation and Transfer:
  • Energy can change from one form to another
  • Example: A lightbulb transforms electrical energy into radiant and thermal energy
  • Energy can be transferred from one object to another
  • Example: Kinetic energy transferred when one player tackles another in a sport

Energy Through a System (Newton's Cradle)

• A system where energy transformations occur
• The red ball's initial potential energy transforms into kinetic energy when released
• Kinetic energy is transferred from ball to ball until the last ball
• The last ball converts kinetic energy back into potential energy
• In a perfect system energy is neither created nor destroyed
• In reality, energy is lost as sound and thermal energy

3.3 Law of Conservation of Energy

• The total energy of a system remains constant throughout
• Start energy = End energy (in an ideal theoretical system)
• Real systems: Energy gets converted into other forms: thermal, sound, mechanical

3.4 Energy Efficiency

• Measures how effectively input energy transforms into useful output
• Usually expressed as a percentage
• Formula: (Useful energy / Consumed energy) x 100
• Higher percentage means more efficient energy use
• Example: A light bulb, 90% of electrical energy transforms into light, 10% lost as heat

Improving Energy Efficiency

• Use Energy-Efficient Technology: Use LED lighting, inverter motors
• Implement Smart Control Systems: Smart thermostats, smart plugs to adjust energy consumption
• Upgrade Insulation and Materials: Reduces heat loss for appliances (refrigerators, ovens)
• Regular Maintenance: Keeps appliances running efficiently (e.g. clean refrigerator coils)
• Optimize Usage Settings: Use suitable settings for appliances
• Reduce Standby Power Consumption: Use power strips, unplug devices not in use
• Consider Renewable Energy Sources: use solar power

3.5 Distinction Between Temperature and Heat

• Thermal Energy: The total energy of moving particles in an object
• Temperature: A measure of the average kinetic energy of particles
• Heat: The transfer of thermal energy from a warmer object to a cooler object
• Example: Ice feels cold because thermal energy is transferred from your hand into the ice (meaning heat flows from your warmer hand to the colder ice)

Examples and Calculations (from provided document)

• Examples show how to calculate energy efficiency of a lawnmower
• Also explores how to determine if cubes made from different materials will have different temperatures after 24 hours