Power & work done

• What are the two definitions of power mentioned in the video?

  Power is the rate at which energy is transferred and the rate at which work is done.
• What is the equation for power when considering energy transferred?

  Power = energy transferred / time.
• What is the equation for power when considering work done?

  Power = work done / time.
• How is work done defined in the context of power?

  Work done is a measure of energy transferred when a force moves an object over a distance.
• If you push a car down the road, what term describes the energy required?

  It is referred to as the work done.
• How is power measured?

  Power is measured in watts.
• What units are used to measure energy transferred and work done?

  Energy transferred and work done are measured in joules.
• How is time measured in the context of power?

  Time is measured in seconds.
• How do you calculate the power of a lamp using energy transferred?

  • Use the equation: Power = energy transferred / time
  • Example: For a lamp transferring 1200 joules over 20 seconds:
  • Power = 1200 J / 20 s = 60 watts
• How do you calculate the power of a lamp using work done?

  • Use the equation: Power = work done / time
  • Example: If 9 kilojoules of work is done over 20 seconds:
  • Convert 9 kJ to joules: 9 kJ = 9000 J
  • Power = 9000 J / 20 s = 450 watts
• If a lamp transfers 1200 joules over 20 seconds, what is its power?

  60 watts.
• If another lamp uses 1500 joules over 30 seconds, what is its power?

  50 watts.
• How much energy is transferred by an 1100 watt microwave running for three minutes?

  198,000 joules or 198 kilojoules.
• What is the power used if you do 9 kilojoules of work over 20 seconds?

  450 watts.
• How do you convert minutes to seconds for calculations?

  Multiply the number of minutes by 60.
• What are the steps to calculate energy transferred using power and time?

  1. Rearrange the equation: Energy transferred = Power × Time
  2. Convert time to seconds if necessary.
  3. Substitute values into the equation.
  4. Calculate the energy transferred.
• What are the steps to calculate power using work done and time?

  1. Use the equation: Power = Work done / Time
  2. Convert work done to joules if necessary.
  3. Substitute values into the equation.
  4. Calculate the power used.