Physics

• How does kinetic energy change with velocity?


  Kinetic energy increases with the square of the velocity.
• What is the formula for gravitational potential energy?


  $GPE =$$m \cdot g \cdot h$
• What are the three main mechanisms of heat transfer?


  • Conduction
  • Convection
  • Radiation
• What is a key characteristic of efficiency in real-world systems?


  Efficiency is always less than 100% in real-world systems due to energy losses.
• Why is perfect efficiency impossible?


  Perfect efficiency (100%) is impossible due to energy losses.
• What is the formula for calculating efficiency in physics?

  $\text{Efficiency} =$$\frac{\text{Useful output energy}}{\text{Total input energy}} \times 100\%$
• What are the factors affecting efficiency in physical systems?


  1. Friction
  2. Heat loss
  3. Electrical resistance
  4. Material properties
  5. Design and construction
  6. Operating conditions
• What are some examples of renewable energy sources?


  • Wind
  • Solar
  • Geothermal
  • Hydropower
  • Biomass
• How can the efficiency of solar panels in the UK be improved?


  By orienting the panels to face south
• What happens to solar panel efficiency as temperature increases?


  Efficiency decreases as temperature increases
• What is the impact of regular cleaning on solar panel performance?


  It removes dirt and debris that can block sunlight
• What are the ideal conditions for solar panel efficiency?


  Cool, sunny days
• During which season would solar panels be most efficient in the UK?


  Spring
• What is geothermal energy?


  Heat derived from the Earth's core
• What are the advantages of geothermal energy?


  Consistent power output, low emissions, small land footprint
• What are the challenges associated with geothermal energy?


  Limited to specific geographic locations and high initial costs
• How does the location dependency of geothermal energy differ from wind and solar energy?


  Geothermal energy is limited to specific geological areas, while wind and solar can be harnessed in more locations.
• How can energy be transformed in a closed system?


  Energy can be converted from one form to another, but the total amount remains constant.
• What does the law of conservation of energy state?


  The law states that energy cannot be created or destroyed, only converted from one form to another.
• In a pendulum, how does energy change forms?


  Energy constantly changes between potential and kinetic forms, but the total energy remains constant.
• What is the definition of power?


  Power is the rate at which energy is transferred or converted.
• How much energy does a 60W light bulb use if it is on for 2 hours?


  The energy used is $E =$$60\,\mathrm{W} \times (2 \times 3600\,\mathrm{s}) =$$432,000\,\mathrm{J} =$$432\,\mathrm{kJ}$.
• What does the photograph of the two buildings illustrate?

  The difference in thermal energy loss between poorly and well-insulated buildings
• What is the main focus of the video regarding buildings?

  How quickly a building loses thermal energy
• What is the first main factor affecting how quickly a building cools down?

  The thermal conductivity of the walls
• What does a higher thermal conductivity of a material indicate?

  A higher rate of energy transfer by conduction across that material
• What are modern houses typically built from?

  An external brick wall and an internal Breeze block wall
• What is the purpose of packing the cavity between walls with insulating material?

  To reduce the overall thermal conductivity of the wall
• How much can insulating material reduce the overall thermal conductivity of a wall?

  By up to 10 times
• How do single glazed windows compare to double glazed windows in terms of thermal conductivity?

  Single glazed windows have a higher thermal conductivity than double glazed windows
• What is one way to reduce thermal energy escape through the roof of a house?

  Using loft insulation
• What effect does loft insulation have on thermal energy transfer?


  It reduces the rate at which thermal energy passes through
• What are two methods to reduce thermal energy transfer from a house?

  Using materials with low thermal conductivity and building thick walls
• What are the factors that affect the cooling of a building?

  • Thermal conductivity of the walls
  • Quality of windows (single vs. double glazed)
  • Insulation in the roof (loft insulation)
  • Thickness of the walls
• What is the overall goal of using low thermal conductivity materials in building construction?

  To reduce thermal energy loss and heating costs
• What is the practical method to determine the specific heat capacity of a material?

  • Place a beaker on a balance and zero it.
  • Add the material (e.g., vegetable oil) and record its mass.
  • Insert a thermometer and immersion heater into the material.
  • Measure the starting temperature.
  • Wrap the beaker in insulating foam.
  • Connect a joule meter and power pack to the immersion heater.
  • Allow the setup to run for about 30 minutes.
  • Record the total energy passed into the heater and the final temperature.
• What is the purpose of wrapping the beaker in insulating foam?

  To reduce thermal energy transfer to the surroundings.
• How do you calculate the specific heat capacity of a material?

  The specific heat capacity is calculated using the formula: $c =$$\frac{\Delta Q}{m \Delta T}$.
• If 0.95 kg of oil is heated from 20° C to 75° C with 87258 J of energy, what is the specific heat capacity?

  The specific heat capacity is $1,670 \text{ J/kg°C}$.
• What are the main sources of inaccuracies in determining specific heat capacity?

  • Thermal energy loss to the air.
  • Incomplete energy transfer from the immersion heater to the oil.
  • Incorrect thermometer readings.
  • Uneven thermal distribution in the oil.