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 120 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 60 J · Wasted: 60 J
2. A machine is supplied with 240 J of total energy and transfers 204 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 204 J · Wasted: 36 J
3. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 108 J · Wasted: 252 J
4. A machine is supplied with 340 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 51 J · Wasted: 289 J
5. A machine is supplied with 160 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 96 J · Wasted: 64 J
6. A machine is supplied with 80 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 20 J · Wasted: 60 J
7. A machine is supplied with 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 6 J · Wasted: 34 J
8. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 51 J · Wasted: 9 J
9. A machine is supplied with 480 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 288 J · Wasted: 192 J
10. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 84 J · Wasted: 196 J
11. A machine is supplied with 380 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 114 J · Wasted: 266 J
12. A machine is supplied with 300 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 180 J · Wasted: 120 J

12 questions · Seed 104732 · 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 120 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (60 ÷ 120) × 100% = 50%.
2. A machine is supplied with 240 J of total energy and transfers 204 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (204 ÷ 240) × 100% = 85%.
3. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (108 ÷ 360) × 100% = 30%.
4. A machine is supplied with 340 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (51 ÷ 340) × 100% = 15%.
5. A machine is supplied with 160 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (96 ÷ 160) × 100% = 60%.
6. A machine is supplied with 80 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (20 ÷ 80) × 100% = 25%.
7. A machine is supplied with 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (6 ÷ 40) × 100% = 15%.
8. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (51 ÷ 60) × 100% = 85%.
9. A machine is supplied with 480 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (288 ÷ 480) × 100% = 60%.
10. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (84 ÷ 280) × 100% = 30%.
11. A machine is supplied with 380 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (114 ÷ 380) × 100% = 30%.
12. A machine is supplied with 300 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (180 ÷ 300) × 100% = 60%.

12 questions · Seed 104732 · 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 120 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 60 J · Wasted: 60 J
2. A machine is supplied with 240 J of total energy and transfers 204 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 204 J · Wasted: 36 J
3. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 108 J · Wasted: 252 J
4. A machine is supplied with 340 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 51 J · Wasted: 289 J
5. A machine is supplied with 160 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 96 J · Wasted: 64 J
6. A machine is supplied with 80 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 20 J · Wasted: 60 J
7. A machine is supplied with 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 6 J · Wasted: 34 J
8. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 51 J · Wasted: 9 J
9. A machine is supplied with 480 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 288 J · Wasted: 192 J
10. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 84 J · Wasted: 196 J
11. A machine is supplied with 380 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 114 J · Wasted: 266 J
12. A machine is supplied with 300 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 180 J · Wasted: 120 J

12 questions · Seed 104732 · 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 120 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (60 ÷ 120) × 100% = 50%.
2. A machine is supplied with 240 J of total energy and transfers 204 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (204 ÷ 240) × 100% = 85%.
3. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (108 ÷ 360) × 100% = 30%.
4. A machine is supplied with 340 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (51 ÷ 340) × 100% = 15%.
5. A machine is supplied with 160 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (96 ÷ 160) × 100% = 60%.
6. A machine is supplied with 80 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (20 ÷ 80) × 100% = 25%.
7. A machine is supplied with 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (6 ÷ 40) × 100% = 15%.
8. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (51 ÷ 60) × 100% = 85%.
9. A machine is supplied with 480 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (288 ÷ 480) × 100% = 60%.
10. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (84 ÷ 280) × 100% = 30%.
11. A machine is supplied with 380 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (114 ÷ 380) × 100% = 30%.
12. A machine is supplied with 300 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (180 ÷ 300) × 100% = 60%.

12 questions · Seed 104732 · Age guidance, not curriculum certification