lesson 11 — 2.10

Energy

Calculations + §2.6 & 2.7

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Slide 1: Tekstslide

energy calculationsMiddelbare schoolhavo, vwoLeerjaar 1

In deze les zitten 20 slides, met tekstslides en 1 video.

Onderdelen in deze les

Energy

Calculations + §2.6 & 2.7

Slide 1 - Tekstslide

Slide 2 - Video

In pairs of two

Step 1)

For 10 minutes

One of you reads and takes notes of §2.6.
The other reads and takes notes of §2.7

Step 2)

Discuss what you learned

Go over each others notes
think of one question per paragraph

Step 3

Share your notes with another pair close to you

Slide 3 - Tekstslide

Recap

Slide 4 - Tekstslide

Useful energy

wasted energy

Efficiency

Slide 5 - Tekstslide

E f f i c i e n c y = (\frac{​ u s e f u l e n e r g y ​ ​}{​ t o t a l e n e r g y ​}) \cdot 100

Slide 6 - Tekstslide

E f f i c i e n c y = (\frac{​ u s e f u l e n e r g y ​ ​}{​ t o t a l e n e r g y ​}) \cdot 100

= (\frac{​ E ^{​ u ​ ​} ​ ​}{​ E ^{​ t ​ ​} ​}) \cdot 100

η: efficiency (%)
Eu: Energy useful (J)
Et: energy total (J)

Slide 7 - Tekstslide

2.10

Energy snaky diagram

Slide 8 - Tekstslide

Which lamp is more efficient?

Slide 9 - Tekstslide

Slide 10 - Tekstslide

Calculations — Exercise 1

Consider a machine that puts out 6070 joules of useful work. As a by product it also produces 2500Joules of heat.

Calculate the efficiency of this machine.

Slide 11 - Tekstslide

Consider a machine that puts out 6070 joules of useful work. As a by product it also produces 2500Joules of heat.

Calculate the efficiency of this machine.

Given

Eu = 6070 J
Ew = 2500 J
Et = 6700 + 2500 = 8570 J

Asked

Calculate the efficiency of this machine

Fromula

Calculation

Slide 12 - Tekstslide

Consider a machine that puts out 6070 joules of useful work. As a by product it also produces 2500Joules of heat.

Calculate the efficiency of this machine.

Given

Eu = 6070 J
Ew = 2500 J
Et = 6700 + 2500 = 8570 J

Asked

Calculate the efficiency of this machine

Fromula

Calculation

= (\frac{​ E ^{​ u ​ ​} ​ ​}{​ E ^{​ t ​ ​} ​}) \cdot 100

Slide 13 - Tekstslide

Consider a machine that puts out 6070 joules of useful work. As a by product it also produces 2500Joules of heat.

Calculate the efficiency of this machine.

Given

Eu = 6070 J
Ew = 2500 J
Et = 6700 + 2500 = 8570 J

Asked

Calculate the efficiency of this machine

Fromula

Calculation

= (\frac{​ E ^{​ u ​ ​} ​ ​}{​ E ^{​ t ​ ​} ​}) \cdot 100

= (\frac{​ 6 0 7 0 ​ ​}{​ 8 5 7 0 ​}) \cdot 100

% = 70,8 %

Slide 14 - Tekstslide

Calculations — Exercise 2

A machine has an efficiency of 25 %. It creates 350 joules of useful work. Calculate its total energy input.

Slide 15 - Tekstslide

A machine has an efficiency of 25 %. It creates 350 joules of useful work. Calculate its total energy input.

Given

η = 25 %
E_useful= 350 J

Asked

Calculate the total energy input of this machine

Fromula

Calculation

Slide 16 - Tekstslide

Given

η = 25 %
E_useful= 350 J

Asked

Calculate the total energy input of this machine

Fromula

Calculation

Slide 17 - Tekstslide

Calculations — Exercise 3

An average car uses 8.9 liters of gasoline per 100 kilometre. One liter of gasoline contains 31536000 joules. If a car drives 150 kilometre, and during this journey it creates 32450544 joules of heat and sound energy combined, what would be its efficiency?

Slide 18 - Tekstslide

An average car uses 8.9 liters of gasoline per 100 kilometre. One liter of gasoline contains 31536000 joules. If a car drives 150 kilometre, and during this journey it creates 32450544 joules off heat and sound energy combined, what would be its efficiency?

Given

8.9 liters per 100 kilometer
one liter contains 3153600 joules
a car drives 150 kilometrer
E_Wasted = 32450544 J
E_total= 8.9 x 3153600 x 1.5 = 42100560 J
E_useful= 42100560 - 32450544 =

9650016 J

Slide 19 - Tekstslide

Given

8.9 liters per 100 kilometer
one liter contains 3153600 joules
a car drives 150 kilometrer
E_Wasted = 32450544 J
E_total= 8.9 x 3153600 x 1.5 = 42100560 J
E_useful= 42100560 - 32450544 =

9650016 J

Slide 20 - Tekstslide