Transfer of energy and work done

• Work done: use of a force to move an object in the direction of the force
• Conditions for work to be done:

  1. There is a force acting on an object.

  2. The object moves.

  3. The object moves in the direction of the force
• Energy is the ability to do work
• Living things need energy for processes that keep them alive and active, while non-living things also need energy to work
• The amount of work done depends on the size of the force applied and the distance moved by the object in the direction of the force
• Work done = joule (J)

  one joule is the work done when a force of one Newton moves an object by one meter in the direction of the force
• Potential energy is stored energy.
• Gravitational potential energy is the energy stored in an object because of its height above ground level.
• Work done, J = Force x distance= Fxd
• when one joule of work is done, one joule of energy is transferred
• GPE, J = mass of body x gravitational field strength, N/kg x height = mgh
• Phrasing technique:

  Energy is transferred by "Any 4 ways to transfer" to the "Any 6 energy stores of the object"

  Example:

  Energy is transferred mechanically to the kinetic potential energy store of the ball
• 4 ways to transfer energy:

  1. Heating
  2. Propagation of waves (electromagnetic/mechanical)
  3. Work done by force (mechanically)
  4. Electric current
• 6 stores of energy:

  1. Kinetic store
  2. Gravitational potential store
  3. Elastic potential store
  4. Chemical potential store
  5. Thermal store
  6. Nuclear store
• principle of conservation of energy:

  • energy can neither be created not destroyed in any process. It can be converted from one form to another or transferred from one body to another,
  • It can be converted from one form to another or transferred from one body to another, but the total amount remains constant