Energy Stores and Systems

• A system is an object or group of objects
• there are changes in the way energy is stored when a system changes
• When a system changes, energy is transferred
• the net change in the total energy of a closed system is always 0
• Object projected upwards:

  • Energy transfer from chemical energy of the person's arm throwing the ball
  • to the kinetic energy store of the ball and arm
• A moving object hitting an obstacle - when the object collides with the obstacle, energy is is converted to:

  • the kinetic store of the obstacle
  • the thermal store of the object and the obstacle (the particles in the object and the obstacle vibrate more
• an object accelerated by a constant force - energy is required to accelerate the object, which could be chemical, thermal. or electrical. (the situation will determine the specific type of energy). This energy will then be converted into kinetic energy which is used to accelerate the object
• a vehicle slowing down - during this process, energy is dissipated through heat and sound
• bringing water to boil in an electric kettle - transferring electrical energy into thermal energy, which is used to heat up the water
• heating an object transfers energy ti the objects internal store of energy (the sum of the energy in kinetic and chemical stores of its particles)
• now joule of work or one soul of energy is transferred when a force of one newton causes a body to move through a distance of one metre
• electrical work done means that energy has been transferred when a current flows
• kinetic store - the energy stored by an objects movement
• gravitational potential store - the energy stored in objects raised above the earths surface. this energy exists because of earths gravitational field
• chemical store - the energy stored by the chemical bonds between atoms
• elastic potential store - the energy stored when an object is being stretched or compressed
• nuclear store - the energy stored in the nucleus of an atom. the energy in the nuclear store can be released by radioactive decay
• internal / thermal store - the internal store od the energy is the sum of the kinetic energy stored in the particles of an object and the chemical energy stored in chemical bonds between particles in the object