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 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
2. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 152 J · Wasted: 8 J
3. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 56 J · Wasted: 104 J
4. A machine is supplied with 260 J of total energy and transfers 39 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 39 J · Wasted: 221 J
5. A machine is supplied with 120 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 114 J · Wasted: 6 J
6. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 63 J · Wasted: 77 J
7. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 234 J · Wasted: 26 J
8. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 270 J · Wasted: 30 J
9. A machine is supplied with 400 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 240 J · Wasted: 160 J
10. A machine is supplied with 60 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 15 J · Wasted: 45 J
11. A machine is supplied with 100 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 20 J · Wasted: 80 J
12. A machine is supplied with 360 J of total energy and transfers 324 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 324 J · Wasted: 36 J

12 questions · Seed 104746 · 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 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%.
2. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (152 ÷ 160) × 100% = 95%.
3. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (56 ÷ 160) × 100% = 35%.
4. A machine is supplied with 260 J of total energy and transfers 39 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (39 ÷ 260) × 100% = 15%.
5. A machine is supplied with 120 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (114 ÷ 120) × 100% = 95%.
6. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (63 ÷ 140) × 100% = 45%.
7. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (234 ÷ 260) × 100% = 90%.
8. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (270 ÷ 300) × 100% = 90%.
9. A machine is supplied with 400 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 400) × 100% = 60%.
10. A machine is supplied with 60 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (15 ÷ 60) × 100% = 25%.
11. A machine is supplied with 100 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (20 ÷ 100) × 100% = 20%.
12. A machine is supplied with 360 J of total energy and transfers 324 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (324 ÷ 360) × 100% = 90%.

12 questions · Seed 104746 · 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 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
2. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 152 J · Wasted: 8 J
3. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 56 J · Wasted: 104 J
4. A machine is supplied with 260 J of total energy and transfers 39 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 39 J · Wasted: 221 J
5. A machine is supplied with 120 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 114 J · Wasted: 6 J
6. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 63 J · Wasted: 77 J
7. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 234 J · Wasted: 26 J
8. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 270 J · Wasted: 30 J
9. A machine is supplied with 400 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 240 J · Wasted: 160 J
10. A machine is supplied with 60 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 15 J · Wasted: 45 J
11. A machine is supplied with 100 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 20 J · Wasted: 80 J
12. A machine is supplied with 360 J of total energy and transfers 324 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 324 J · Wasted: 36 J

12 questions · Seed 104746 · 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 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%.
2. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (152 ÷ 160) × 100% = 95%.
3. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (56 ÷ 160) × 100% = 35%.
4. A machine is supplied with 260 J of total energy and transfers 39 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (39 ÷ 260) × 100% = 15%.
5. A machine is supplied with 120 J of total energy and transfers 114 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (114 ÷ 120) × 100% = 95%.
6. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (63 ÷ 140) × 100% = 45%.
7. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (234 ÷ 260) × 100% = 90%.
8. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (270 ÷ 300) × 100% = 90%.
9. A machine is supplied with 400 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 400) × 100% = 60%.
10. A machine is supplied with 60 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (15 ÷ 60) × 100% = 25%.
11. A machine is supplied with 100 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (20 ÷ 100) × 100% = 20%.
12. A machine is supplied with 360 J of total energy and transfers 324 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (324 ÷ 360) × 100% = 90%.

12 questions · Seed 104746 · Age guidance, not curriculum certification