1.1.4 Power

• power = energy transferred / time
• power = work done / time
• What is power measured in?

  Watts.
• What is energy transferred measured in?

  Joules.
• What is time measured in?

  Seconds.
• What is work done measured in?

  Joules.
• 1J per second is equal to what?


  1 watt.
• What is power?

  Power is the rate at which energy is transferred, or the rate at which work is done.
• What does work done mean?

  The terms 'Work' or 'work done' refer to the energy transfer that occurs when a force is used to move an object by a certain distance
• A toaster consumes 40,500J in 45s, what is its power consumption?

  900W.
• A 25W light bulb was turned on and consumed 650J of energy before it was turned off. How long was the light bulb on for?

  26s.
• MJ to J

  x1000000
• J to MJ

  /1000000
• A wind turbine generates 150MJ of energy in one minute. What is the rate of power generation?

  2500000W
• A phone battery can hold 18,000 joules of energy, and the phone charger has a power rating of 2 W. How many hours will it take to charge the phone from completely flat to full battery?

  2.5 hours.