Topic 8 - Energy – forces doing work

    Cards (10)

    • What is a system?
      A single object.
    • When a system changes, energy is transferred.
    • What are the different ways in which energy can be transferred?
      energy can be transferred through:
      Heating, work done by forces, by electrical equipment.
    • when a force moves an object through a distance, work is done on the object, and energy is transferred. The unit used to measure the energy is joules (J).
    • What is the formula for work done?
      Work done = force x distance
    • mechanical processes become wasteful when they cause a temperature rise dissipating energy in heating the surroundings.
    • What is power?
      the rate at which energy is transferred. EG: An electric heater does 60J per second = 60 Watts.
    • What is the formula for power?
      Power = Work done / time taken.
    • one watt = one joule per second.
    • What is the formula for efficiency?
      efficiency = useful energy/ total energy * 100.