Power and work done

• What is the focus of today's video?

  Understanding power and its calculations
• How many definitions of power are there?

  Two definitions
• What is the first definition of power?

  Rate at which energy is transferred
• What is the equation for power based on energy transferred?

  Power = energy transferred / time
• What is the second definition of power?

  Rate at which work is done
• What is the equation for power based on work done?

  Power = work done / time
• What does "work done" refer to?

  Energy transferred using a force
• How is work done illustrated in a real-world example?

  Pushing a car down the road
• How is power measured?

  In watts
• How are energy transferred and work done measured?

  In joules
• How is time measured in these equations?

  In seconds
• How do you compare the power of two lamps?

  • Use the energy transferred equation
  • Calculate power for each lamp
  • Compare the results
• What is the power of the left lamp that transfers 1200 joules over 20 seconds?

  60 watts
• What is the power of the right lamp that uses 1500 joules over 30 seconds?

  50 watts
• What does a lamp's label indicate?

  Its power in watts
• How do you calculate energy transferred by an 1100 watt microwave running for three minutes?

  Energy transferred = power × time
• How do you convert three minutes to seconds?

  180 seconds
• What is the energy transferred by an 1100 watt microwave in 180 seconds?

  198,000 joules
• How do you convert joules to kilojoules?

  Divide by 1000
• What is the energy transferred by the microwave in kilojoules?

  198 kilojoules
• How do you calculate power when doing 9 kilojoules of work over 20 seconds?

  Power = work done / time
• What is the power used when doing 9 kilojoules of work in 20 seconds?

  450 watts
• What is the key takeaway from the video?

  • Power has two definitions
  • Power is calculated using specific equations
  • Units for power, energy, and time are important