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 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 88 J · Wasted: 352 J
2. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 112 J · Wasted: 28 J
3. A machine is supplied with 200 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 160 J · Wasted: 40 J
4. A machine is supplied with 400 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 80 J · Wasted: 320 J
5. 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
6. A machine is supplied with 360 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 54 J · Wasted: 306 J
7. A machine is supplied with 280 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 56 J · Wasted: 224 J
8. A machine is supplied with 280 J of total energy and transfers 70 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 70 J · Wasted: 210 J
9. 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
10. A machine is supplied with 40 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 36 J · Wasted: 4 J
11. A machine is supplied with 180 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 63 J · Wasted: 117 J
12. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 48 J · Wasted: 72 J

12 questions · Seed 50 · 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 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (88 ÷ 440) × 100% = 20%.
2. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 140) × 100% = 80%.
3. A machine is supplied with 200 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 200) × 100% = 80%.
4. A machine is supplied with 400 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 400) × 100% = 20%.
5. 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%.
6. A machine is supplied with 360 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (54 ÷ 360) × 100% = 15%.
7. A machine is supplied with 280 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (56 ÷ 280) × 100% = 20%.
8. A machine is supplied with 280 J of total energy and transfers 70 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (70 ÷ 280) × 100% = 25%.
9. 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%.
10. A machine is supplied with 40 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 40) × 100% = 90%.
11. A machine is supplied with 180 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (63 ÷ 180) × 100% = 35%.
12. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 120) × 100% = 40%.

12 questions · Seed 50 · 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 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 88 J · Wasted: 352 J
2. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 112 J · Wasted: 28 J
3. A machine is supplied with 200 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 160 J · Wasted: 40 J
4. A machine is supplied with 400 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 80 J · Wasted: 320 J
5. 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
6. A machine is supplied with 360 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 54 J · Wasted: 306 J
7. A machine is supplied with 280 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 56 J · Wasted: 224 J
8. A machine is supplied with 280 J of total energy and transfers 70 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 70 J · Wasted: 210 J
9. 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
10. A machine is supplied with 40 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 36 J · Wasted: 4 J
11. A machine is supplied with 180 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 63 J · Wasted: 117 J
12. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 48 J · Wasted: 72 J

12 questions · Seed 50 · 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 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (88 ÷ 440) × 100% = 20%.
2. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 140) × 100% = 80%.
3. A machine is supplied with 200 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 200) × 100% = 80%.
4. A machine is supplied with 400 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 400) × 100% = 20%.
5. 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%.
6. A machine is supplied with 360 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (54 ÷ 360) × 100% = 15%.
7. A machine is supplied with 280 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (56 ÷ 280) × 100% = 20%.
8. A machine is supplied with 280 J of total energy and transfers 70 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (70 ÷ 280) × 100% = 25%.
9. 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%.
10. A machine is supplied with 40 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 40) × 100% = 90%.
11. A machine is supplied with 180 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (63 ÷ 180) × 100% = 35%.
12. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 120) × 100% = 40%.

12 questions · Seed 50 · Age guidance, not curriculum certification