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 180 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 36 J · Wasted: 144 J
2. A machine is supplied with 280 J of total energy and transfers 210 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 210 J · Wasted: 70 J
3. A machine is supplied with 440 J of total energy and transfers 352 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 352 J · Wasted: 88 J
4. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 224 J · Wasted: 56 J
5. 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
6. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 125 J · Wasted: 375 J
7. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 221 J · Wasted: 39 J
8. A machine is supplied with 440 J of total energy and transfers 198 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 198 J · Wasted: 242 J
9. A machine is supplied with 20 J of total energy and transfers 5 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 5 J · Wasted: 15 J
10. A machine is supplied with 500 J of total energy and transfers 375 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 375 J · Wasted: 125 J
11. A machine is supplied with 20 J of total energy and transfers 3 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 3 J · Wasted: 17 J
12. A machine is supplied with 300 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 240 J · Wasted: 60 J

12 questions · Seed 104742 · 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 180 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 180) × 100% = 20%.
2. A machine is supplied with 280 J of total energy and transfers 210 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (210 ÷ 280) × 100% = 75%.
3. A machine is supplied with 440 J of total energy and transfers 352 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (352 ÷ 440) × 100% = 80%.
4. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (224 ÷ 280) × 100% = 80%.
5. 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%.
6. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (125 ÷ 500) × 100% = 25%.
7. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (221 ÷ 260) × 100% = 85%.
8. A machine is supplied with 440 J of total energy and transfers 198 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (198 ÷ 440) × 100% = 45%.
9. A machine is supplied with 20 J of total energy and transfers 5 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (5 ÷ 20) × 100% = 25%.
10. A machine is supplied with 500 J of total energy and transfers 375 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (375 ÷ 500) × 100% = 75%.
11. A machine is supplied with 20 J of total energy and transfers 3 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (3 ÷ 20) × 100% = 15%.
12. A machine is supplied with 300 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 300) × 100% = 80%.

12 questions · Seed 104742 · 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 180 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 36 J · Wasted: 144 J
2. A machine is supplied with 280 J of total energy and transfers 210 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 210 J · Wasted: 70 J
3. A machine is supplied with 440 J of total energy and transfers 352 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 352 J · Wasted: 88 J
4. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 224 J · Wasted: 56 J
5. 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
6. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 125 J · Wasted: 375 J
7. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 221 J · Wasted: 39 J
8. A machine is supplied with 440 J of total energy and transfers 198 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 198 J · Wasted: 242 J
9. A machine is supplied with 20 J of total energy and transfers 5 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 5 J · Wasted: 15 J
10. A machine is supplied with 500 J of total energy and transfers 375 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 375 J · Wasted: 125 J
11. A machine is supplied with 20 J of total energy and transfers 3 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 3 J · Wasted: 17 J
12. A machine is supplied with 300 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 240 J · Wasted: 60 J

12 questions · Seed 104742 · 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 180 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 180) × 100% = 20%.
2. A machine is supplied with 280 J of total energy and transfers 210 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (210 ÷ 280) × 100% = 75%.
3. A machine is supplied with 440 J of total energy and transfers 352 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (352 ÷ 440) × 100% = 80%.
4. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (224 ÷ 280) × 100% = 80%.
5. 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%.
6. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (125 ÷ 500) × 100% = 25%.
7. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (221 ÷ 260) × 100% = 85%.
8. A machine is supplied with 440 J of total energy and transfers 198 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (198 ÷ 440) × 100% = 45%.
9. A machine is supplied with 20 J of total energy and transfers 5 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (5 ÷ 20) × 100% = 25%.
10. A machine is supplied with 500 J of total energy and transfers 375 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (375 ÷ 500) × 100% = 75%.
11. A machine is supplied with 20 J of total energy and transfers 3 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (3 ÷ 20) × 100% = 15%.
12. A machine is supplied with 300 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 300) × 100% = 80%.

12 questions · Seed 104742 · Age guidance, not curriculum certification