physics gcse

• What is a system in terms of energy?

  An object or group of objects
• What is energy dissipation?

  When energy is not transferred usefully but is wasted (often as thermal energy)
• What are the seven energy stores?

  • Kinetic
  • (Internal) Thermal
  • Chemical
  • Gravitational Potential
  • Elastic Potential
  • Electrostatic
  • Magnetic
• What is a closed system?

  Systems where neither matter nor energy can enter or leave
• What does 'doing work' result in?

  A transfer of energy
• What is the unit of energy?

  Joule
• What are the four ways energy can be transferred between stores?

  1. By mechanical work
  2. By electrical work
  3. By heating
  4. By radiation
• What is the conservation of energy principle?

  Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed
• What is the equation linking kinetic energy, mass and velocity?

  $KE =$$0.5 \times \text{mass} \times (\text{velocity})^2$
• What are the units for velocity?

  Meters per second (m/s)
• What are the units for mass?

  Kilograms (kg)
• What is the equation linking elastic potential energy, the spring constant and extension?

  $PE =$$0.5 \times \text{spring constant} \times (\text{extension})^2$
• What are the units for the spring constant?

  Newtons per metre (N/m)
• What are the units for extension?

  Metres (m)
• What is the equation linking gravitational potential energy, mass, gravity and height?

  $Ep =$$mgh$
• What are the units for gravitational field strength?

  Newtons per kg (N/kg)
• What are the units for height?

  Metres (m)
• What is conduction?

  The process by which vibrating particles transfer energy to neighbouring particles
• What is thermal conductivity?

  A measure of how quickly energy is transferred through a material by conduction
• What is convection?

  Where energetic particles move away from hotter to cooler regions
• What does the symbol ∆ mean?

  Change
• What is specific heat capacity of a substance?

  The amount of energy required to raise the temperature of 1 kg of the substance by 1° Celsius
• What are the units for specific heat capacity?

  Joules per kilogram per °C (J/kg/°C)
• What is power?

  The rate at which energy is transferred or the rate at which work is done
• What is the unit of power?

  Watts (W)
• What is the equation linking power, energy and time?

  $P =$$\frac{E}{t}$
• What is the equation linking power, work done and time?

  $P =$$\frac{W}{t}$
• What are the units for work done?

  Joules (J)
• What happens to waste energy?

  It is dissipated
• How can we reduce unwanted energy transfers?

  • Through lubrication
  • By installation
• Give four examples of insulation that can be used in the house?

  1. Cavity walls
  2. Loft insulation
  3. Double glazing
  4. Draught proofing
• What is the equation for working out efficiency using energy?

  $\text{Efficiency} =$$\frac{\text{useful output energy transfer}}{\text{total input energy transfer}}$
• What is the equation for working out efficiency using power?

  $\text{Efficiency} =$$\frac{\text{useful power output}}{\text{total power input}}$
• What are the units for efficiency?

  There are none
• List the 11 energy resources on Earth.

  1. Coal
  2. Gas
  3. Oil
  4. Nuclear fuel
  5. Biofuel
  6. Wind
  7. Hydroelectricity
  8. Geothermal
  9. The tides

  10. The sun

  11. Water waves
• Name the fossil fuels.

  1. Coal
  2. Gas
  3. Oil
• What is a renewable energy source?

  One that is being (or can be) replenished as it is used
• List three uses of Energy Resources.

  • Transport
  • Electricity generation
  • Heating
• What is density?

  The amount of mass per unit volume
• What is the equation for density?

  $\text{Density} =$$\frac{\text{Mass}}{\text{Volume}}$