P1a

• What is a system in physics?

  An object or a group of objects
• What does it mean if a system has a store of energy?

  It has the ability to do work
• How is energy measured?

  In joules (J)
• What are the types of energy stores?

  • Kinetic
  • Thermal
  • Gravitational potential
  • Elastic potential
  • Magnetic
  • Electrostatic
  • Nuclear
  • Chemical
• What is energy transfer?

  Moving energy from one store to another
• What is work in physics?

  Energy transferred when moving an object
• How is energy transfer measured?

  In joules (J)
• What is the formula for work done?

  Work done = force x distance
• What does energy efficiency represent?

  Useful output energy to total input energy
• What is the efficiency of a petrol engine car?

  0.30 (30%)
• How is power defined in physics?

  Rate at which energy is transferred

  
• What is the unit of power?

  Watts (W)
• What is dissipated energy?

  Energy transferred to a non-useful store
• How can dissipated energy be reduced?

  With lubrication or thermal insulation
• What does the law of conservation of energy state?

  Energy cannot be created or destroyed
• What is specific heat capacity?

  Energy to raise 1 kg by 1 °C
• What is the specific heat capacity of water?

  4,200 J/kg °C
• What are the key quantities and their symbols in physics?

  • Work done (W) - joules (J)
  • Force (F) - Newtons (N)
  • Distance (s) - metres (m)
  • Gravitational potential energy (Ep) - joules (J)
  • Mass (m) - kilograms (kg)
  • Gravitational field strength (g) - N/kg
  • Height (h) - metres (m)
  • Kinetic energy (Ek) - joules (J)
  • Speed (v) - m/s
  • Power (P) - watts (W)
  • Energy transferred (E) - joules (J)
  • Time (t) - seconds (s)
  • Elastic potential energy (Ee) - joules (J)
  • Spring constant (k) - N/m
  • Extension (e) - metres (m)
  • Change in thermal energy (ΔE) - joules (J)
  • Specific heat capacity (c) - J/kg °C
  • Temperature change (Δθ) - °C
• What are the key equations to memorize in physics?

  1. Work done = force x distance
  2. Gravitational potential energy = mass × gravitational field strength × height
  3. Kinetic energy = 0.5 × mass × speed²
  4. Efficiency = useful output energy / total input energy
  5. Power = energy transferred / time
  6. Power = work done / time
  7. Elastic potential energy = 0.5 x spring constant x (extension)²
  8. Change in thermal energy = mass x specific heat capacity x temperature change
• What is the purpose of the required practicals in this topic?

  • RP1: Determine specific heat capacity of a material
  • RP2: Investigate thermal insulation
• How is thermal conductivity investigated?

  By timing how long pins drop off heated rods
• What is conduction in terms of thermal energy transfer?

  Transfer through passing on particle vibrations
• How does thermal conductivity affect energy transfer?

  Higher conductivity means higher energy transfer rate
• What is the rate of cooling in houses?

  How quickly houses cool down
• How can the rate of cooling be reduced in houses?

  By installing cavity wall insulation