Lesson 8 — 2.5 Law of conservation of energy

• The law of conservation of energy
• Voortgezet speciaal onderwijs
• Leerroute 1

The law of

conservation of energy

This lesson

• Phet simulation
• Conservation of energy
•  Usefull & wasted energy

Learning goals

• Explain the law of conservation of energy in your own words
  
• Explain what is meant by useful energy and wasted energy
• Explain what is meant by efficiency

What did we cover

previous lesson?

Energy transfer?

Energy transformation?

Energy transfer  vs  Energy transformation

• Movement of energy from one place to another.

• When energy changes from one type to another.

Link

Watch the upcoming video.

Answer the following questions:

• What are the first two laws of thermodynamics?

• Why is it impossible to create a perpetual motion machine?

Exercise

What are the first two laws of thermodynamics?

• 1) Energy cannot be created or destroyed
  

• 2) Energy tends to spread out
  

Why is it impossible to create a perpetual motion machine?

•  You can't get out more energy then you put in

• Energy always spreads out in ways that aren't useful

The law of

conservation of energy

Energy cannot be created or destroyed

Link

Newtons Cradle

• Useful energy

• wasted energy

• Efficiency
  

The efficiency of a construction lamp

• A construction lamp uses 80 joules/second
  

• It has an efficiency of 25%

80 J of electrical energy

20 J of light energy

The efficiency of a construction lamp

• A construction lamp uses 80 joules/second
  
• It has an efficiency of 25%

60 J of thermal energy

Working independently

Homework (for next week Monday):

The workbook exercises of 2.5 (including E)

Learning goals

• Explain the law of conservation of energy in your own words
  
• Explain what is meant by useful energy and wasted energy
• Explain what is meant by efficiency