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 500 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 100 J · Wasted: 400 J
2. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 144 J · Wasted: 36 J
3. 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
4. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 105 J · Wasted: 35 J
5. A machine is supplied with 440 J of total energy and transfers 330 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 330 J · Wasted: 110 J
6. 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
7. A machine is supplied with 460 J of total energy and transfers 368 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 368 J · Wasted: 92 J
8. A machine is supplied with 100 J of total energy and transfers 95 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 95 J · Wasted: 5 J
9. 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
10. A machine is supplied with 100 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 30 J · Wasted: 70 J
11. A machine is supplied with 360 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 288 J · Wasted: 72 J
12. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 112 J · Wasted: 168 J

12 questions · Seed 104735 · 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 500 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (100 ÷ 500) × 100% = 20%.
2. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 180) × 100% = 80%.
3. 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%.
4. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (105 ÷ 140) × 100% = 75%.
5. A machine is supplied with 440 J of total energy and transfers 330 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (330 ÷ 440) × 100% = 75%.
6. 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%.
7. A machine is supplied with 460 J of total energy and transfers 368 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (368 ÷ 460) × 100% = 80%.
8. A machine is supplied with 100 J of total energy and transfers 95 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (95 ÷ 100) × 100% = 95%.
9. 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%.
10. A machine is supplied with 100 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 100) × 100% = 30%.
11. A machine is supplied with 360 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (288 ÷ 360) × 100% = 80%.
12. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 280) × 100% = 40%.

12 questions · Seed 104735 · 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 500 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 100 J · Wasted: 400 J
2. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 144 J · Wasted: 36 J
3. 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
4. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 105 J · Wasted: 35 J
5. A machine is supplied with 440 J of total energy and transfers 330 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 330 J · Wasted: 110 J
6. 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
7. A machine is supplied with 460 J of total energy and transfers 368 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 368 J · Wasted: 92 J
8. A machine is supplied with 100 J of total energy and transfers 95 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 95 J · Wasted: 5 J
9. 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
10. A machine is supplied with 100 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 30 J · Wasted: 70 J
11. A machine is supplied with 360 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 288 J · Wasted: 72 J
12. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 112 J · Wasted: 168 J

12 questions · Seed 104735 · 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 500 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (100 ÷ 500) × 100% = 20%.
2. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 180) × 100% = 80%.
3. 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%.
4. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (105 ÷ 140) × 100% = 75%.
5. A machine is supplied with 440 J of total energy and transfers 330 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (330 ÷ 440) × 100% = 75%.
6. 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%.
7. A machine is supplied with 460 J of total energy and transfers 368 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (368 ÷ 460) × 100% = 80%.
8. A machine is supplied with 100 J of total energy and transfers 95 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (95 ÷ 100) × 100% = 95%.
9. 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%.
10. A machine is supplied with 100 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 100) × 100% = 30%.
11. A machine is supplied with 360 J of total energy and transfers 288 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (288 ÷ 360) × 100% = 80%.
12. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 280) × 100% = 40%.

12 questions · Seed 104735 · Age guidance, not curriculum certification