Summary H3

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

H3: Energy

What has a flame to do with this chapter?

Chemical energy

Electrical energy

Lesson objectives

• Teminste 2 formules uit H3 op te noemen en uit te leggen wat ze betekenen.
• Tenminste 2 vormen van energie uit het hoofd op te noemen. 
• Zelfstandig kunnen werken aan opgaves via LessonUp

Formulas (Energy)

specific heat

Electrical energy

Efficiency

E=P⋅t

Q=c⋅m⋅ΔT

η=​E(total)​​E(useful)​​⋅100percent

Formulas (Power)

Insulation

Electrical energy

Efficiency

E=P⋅t

Qw=U⋅A⋅ΔT

η=​P(total)​​P(useful)​​⋅100percent

Constants

U

c

Give examples of units matching with quantities.

P	Watt
m	kg

Individual 

Check excersise 6 (hw) -> not completed? -> start now

Otherwise start on excersise 7 -> new homework page 157

Excersise 6

a. Calculate the amount of heat released by the combustion of the natural gas.

Excersise 6

a. Calculate the amount of heat released by the combustion of the natural gas

9.6 *10^6 J 

V(m³)	1	0.30
E (J*10^6)	32	9.6

Excersise 6

b. Calculate the amount of heat taken up by the water.

Given: 28 L -> 28 kg -> 28.000 gram water, c = 4.2, Tstart = 15C, Tend = 85C

Answered: 4.2*28.000*(85-15) = 8.2*10^6 J

Q=c⋅m⋅ΔT

Excersise 6

c. Calculate the efficiency of the combined boiler

8.2*10^6/9.6 *10^6 J * 100 = 86%

η=​E(total)​​E(useful)​​⋅100percent

Homework

Excersise 7,8 and 9 page 157

E-mail with link to the explanation of excersise 11

And a knowledge test about electricity 

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