Physics

• What is a 'system'?


  An object or group of objects
• What can happen to energy?

  It can be stored or transferred
• What is a 'closed system'?

  A system where neither matter nor energy can enter or leave
• What is the net change in the total energy of a closed system?

  Zero
• What is the unit and unit symbol for all types of energy?

  Joules, J
• What is an example of energy stored as elastic potential energy?

  A stretched or compressed spring
• What is an example of energy stored as thermal energy?

  A property an object has because of the kinetic energy of its particles (so everything has a thermal energy store)
• What is another name for a thermal energy store?

  Internal energy store
• What is an example of energy stored as kinetic energy?


  Anything that is moving
• What is an example of energy stored as gravitational potential energy?


  Any object above the ground
• What is an example of energy stored as chemical energy?

  An object that has energy stored due to its chemical composition - e.g batteries, fuels, food
• What is an example of energy stored as electrostatic energy?


  Between two charged objects (i.e. two object that have a potential difference)
• What is an example of energy stored as nuclear energy?

  Radioactive nuclei
• What are the four main ways energy can be transferred between energy stores?

  Heating, radiation, electrical working, mechanical working
• Give an example of how energy is transferred mechanically?

  By a force doing some work
• How is energy transferred by radiating?

  Waves are given out in all directions
• Give an example of how energy is transferred through radiation?

  Light & sound, or anything that is part of the EM spectrum
• Give an example of how energy is transferred electrically?

  A complete circuit allowing charge to flow
• What are the energy store changes when a ball is thrown upwards?

  Kinetic energy store decreases and gravitational potential store increases
• What is another way of saying 'energy transferred'?

  Work done
• What are the energy store changes when a moving object hits an obstacle?

  The moving object has a store of kinetic energy, which is transferred to other stores when it hits the obstacle and suddenly stops. Some of these stores include elastic potential energy in squashing objects and thermal energy into the surroundings
• What are the energy store changes when an object is accelerated by a constant force?

  When a constant force is applied across a distance, work is done on the object. This work is transferred to a store of kinetic energy in the object, causing it to move
• What are the energy store changes when a vehicle applies its brakes to slow down?

  A moving vehicle has a store of kinetic energy, work is done when the brakes are applied and there is a large amount of friction. Energy is transferred to thermal energy stores.
• What are the energy store changes when water is boiled in an electric kettle?

  The kettle transfers a store of electrical energy to thermal energy, which is transferred to the water to heat it up as water has more internal energy.
• What is the word equation for calculating kinetic energy?


  Kinetic Energy = ½ x mass x velocity2
• What is the symbol equation for kinetic energy?


  Ek = ½ mv2
• What is the word equation for calculating gravitational potential energy?


  Gravitational potential energy = mass x gravitational field strength x height
• What is the symbol equation for calculating gravitational potential energy?

  Ep = mgh
• What energy transfer happens when an object is falling?

  Stored gravitational potential energy is transferred to its kinetic energy store
• What two ways can elastic potential energy can be transferred to an object?

  Stretching or squashing
• What does the increase in temperature of a system depend on?

  The mass of the substance, the type of material and the energy input.
• What is the word equation that relates the change in energy of a system, mass, specific heat capacity & temperature change?

  Change in thermal energy = mass x specific heat capacity x temperature change
• What are the units and unit symbols of specific heat capacity?

  Joules per kilogram per degree Celsius, J/kg °C
• What is the specific heat capacity of a substance?

  The amount of energy required to raise the temperature of 1 kg of the substance by 1 °C
• What is power?


  Rate of energy transfer or rate of doing work
• What is the unit and unit symbol of power?

  Watts, W
• How much energy is transferred by 1 watt?

  1 Joule per second
• What does dissipated mean?

  Energy that is not usefully transferred
• What is the principle of conservation of energy?

  Energy cannot be created or destroyed, it can only be transferred usefully, stored or dissipated
• What does it mean when we say that energy is "wasted"?

  When energy is dissipated, so that it is stored in less useful ways