Energy Transfers

• What are the 4 energy transfers

  • Mechanical
  • Electrically
  • Heating
  • Radiation
• What is a mechanical energy transfer?


  By force doing work
• What is electrically energy transfer?

  
  

  Work done by a charge moving
• What is Heating?

  
  

  Because of temperature difference
• Radiation is a wave such as light or sound
• What is the scientific definition of power?

  
  

  Power is the rate at which work is done.
• Power = energy transferred/time
• Power = work done/time
• Energy is measured in Joules ( J )
• Power is measured in Watts ( W )
• Time is measured in Seconds
• 1 Watt + 1 joule per second
• A lawnmower engine does 10 kJ of work in 50 seconds. What is the

  power of the engine?

  Power = Work done/Time

  P = ( 10 x 1000 ) / 50

  P = 200W
• Work done ( energy ) = force x distance
• Work done is measured in Joules ( J )
• Force is measured in Newtons ( N )
• Distance is measured in metres ( m )
• A cyclist peddles a bicycle with a force of 1,000 N moving it 250m. Calculate the work done

  Work done = force x distance

  w = 1000 x 250

  = 250,000J