Energy

• What’s a system ?

  An object or a group of objects
• What are the energy stores?

  Thermal

  Kinetic

  Gravitational potential

  Elastic potential

  Chemical

  Magnetic

  Electrostatic

  Nuclear
• What’s work done?

  Energy transferred
• How can work be done?

  When current flows or by force of moving an object
• What’s the formula for kinetic energy?

  1/2 x mass (kg) x speed (m/s)^2
• What is kinetic energy measured in ?

  Joules
• What’s the equation for elastic potential energy?

  1/2 x spring constant (N/m) x extension ^2 (m)
• What’s the units for elastic potential energy?

  Joules
• What’s the equation for gravitational potential energy?

  Mass (kg) x gravitational field strength (N/kg) x height (m)
• What’s the units for gravitational potential?

  Joules
• What’s specific heat capacity?

  Amount of heat needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius
• What’s the equation for specific heat capacity ?

  change in thermal energy (J) = mass (kg) x specific heat capacity (J/kg °C) x temperature change (°C)
• What’s power?

  The rate at which energy is transferred or the rate which work is done
• What’s the equation for power?

  Power = energy transferred (E) / time (s)

  OR

  Power = work done (J) / time (s)
• What is power measured in ?

  Watts
• What is 1 joule equal to?

  An energy transfer of 1 joule per second = a power of 1 watt
• What’s the conservation of energy?

  Energy can be transferred usefully, stored or dissipated but cannot be created or destroyed
• How to reduce unwanted energy transfers?

  Through lubrication and thermal insulation
• What affects the rate of cooling a building ?

  Thickness and thermal conductivity of its walls
• What’s the equation for efficiency ?

  Useful /total
• How to increase efficiency?

  Reducing wasted energy transfers
• What are renewable energy resources?

  One that can be replenished as it is used - will never run out
• What are non-renewable energy resources?

  Ones that will run out one day
• What’s examples of non renewable energy resources?

  Coal, oil, natural gas
• What’s examples of renewable energy resources?

  solar

  Wind

  Water waves

  Hydroelectricity

  Bio fuels

  Tides

  Geothermal
• What are the uses of energy resources?

  electricity, transport and heating
• What is a drawback of renewable energy?

  Don’t provide as much energy - some are unreliable (weather dependent)