ScienceAges 10-12

Percentage energy efficiency

Calculate the percentage efficiency of a device from useful energy output and total energy input. Review suitability for your learners before teaching.

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Age band:Ages 10-12 Ages 13-15

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Worksheet StudioPractice pack · Ages 10-12

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 399 J · Wasted: 21 J
2. A machine is supplied with 180 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 90 J · Wasted: 90 J
3. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 144 J · Wasted: 216 J
4. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 126 J · Wasted: 14 J
5. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 380 J · Wasted: 20 J
6. A machine is supplied with 320 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 288 J · Wasted: 32 J
7. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 75 J · Wasted: 425 J
8. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 60 J · Wasted: 20 J
9. A machine is supplied with 240 J of total energy and transfers 228 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 228 J · Wasted: 12 J
10. A machine is supplied with 40 J of total energy and transfers 8 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 8 J · Wasted: 32 J
11. A machine is supplied with 360 J of total energy and transfers 342 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 342 J · Wasted: 18 J
12. A machine is supplied with 220 J of total energy and transfers 209 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 209 J · Wasted: 11 J

12 questions · Seed 44 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 10-12

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (399 ÷ 420) × 100% = 95%.
2. A machine is supplied with 180 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 180) × 100% = 50%.
3. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 360) × 100% = 40%.
4. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (126 ÷ 140) × 100% = 90%.
5. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (380 ÷ 400) × 100% = 95%.
6. A machine is supplied with 320 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (288 ÷ 320) × 100% = 90%.
7. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (75 ÷ 500) × 100% = 15%.
8. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (60 ÷ 80) × 100% = 75%.
9. A machine is supplied with 240 J of total energy and transfers 228 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (228 ÷ 240) × 100% = 95%.
10. A machine is supplied with 40 J of total energy and transfers 8 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (8 ÷ 40) × 100% = 20%.
11. A machine is supplied with 360 J of total energy and transfers 342 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (342 ÷ 360) × 100% = 95%.
12. A machine is supplied with 220 J of total energy and transfers 209 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (209 ÷ 220) × 100% = 95%.

12 questions · Seed 44 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 10-12

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 399 J · Wasted: 21 J
2. A machine is supplied with 180 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 90 J · Wasted: 90 J
3. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 144 J · Wasted: 216 J
4. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 126 J · Wasted: 14 J
5. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 380 J · Wasted: 20 J
6. A machine is supplied with 320 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 288 J · Wasted: 32 J
7. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 75 J · Wasted: 425 J
8. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 60 J · Wasted: 20 J
9. A machine is supplied with 240 J of total energy and transfers 228 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 228 J · Wasted: 12 J
10. A machine is supplied with 40 J of total energy and transfers 8 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 8 J · Wasted: 32 J
11. A machine is supplied with 360 J of total energy and transfers 342 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 342 J · Wasted: 18 J
12. A machine is supplied with 220 J of total energy and transfers 209 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 209 J · Wasted: 11 J

12 questions · Seed 44 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 10-12

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (399 ÷ 420) × 100% = 95%.
2. A machine is supplied with 180 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 180) × 100% = 50%.
3. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 360) × 100% = 40%.
4. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (126 ÷ 140) × 100% = 90%.
5. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (380 ÷ 400) × 100% = 95%.
6. A machine is supplied with 320 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (288 ÷ 320) × 100% = 90%.
7. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (75 ÷ 500) × 100% = 15%.
8. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (60 ÷ 80) × 100% = 75%.
9. A machine is supplied with 240 J of total energy and transfers 228 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (228 ÷ 240) × 100% = 95%.
10. A machine is supplied with 40 J of total energy and transfers 8 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (8 ÷ 40) × 100% = 20%.
11. A machine is supplied with 360 J of total energy and transfers 342 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (342 ÷ 360) × 100% = 95%.
12. A machine is supplied with 220 J of total energy and transfers 209 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (209 ÷ 220) × 100% = 95%.

12 questions · Seed 44 · Age guidance, not curriculum certification