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 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 64 J · Wasted: 96 J
2. A machine is supplied with 380 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 57 J · Wasted: 323 J
3. A machine is supplied with 180 J of total energy and transfers 135 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 135 J · Wasted: 45 J
4. A machine is supplied with 240 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 192 J · Wasted: 48 J
5. 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
6. A machine is supplied with 40 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 20 J · Wasted: 20 J
7. A machine is supplied with 440 J of total energy and transfers 110 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 110 J · Wasted: 330 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 80 J of total energy and transfers 16 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 16 J · Wasted: 64 J
10. A machine is supplied with 460 J of total energy and transfers 414 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 414 J · Wasted: 46 J
11. 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
12. A machine is supplied with 380 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 323 J · Wasted: 57 J

12 questions · Seed 104740 · 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 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 160) × 100% = 40%.
2. A machine is supplied with 380 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 380) × 100% = 15%.
3. A machine is supplied with 180 J of total energy and transfers 135 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (135 ÷ 180) × 100% = 75%.
4. A machine is supplied with 240 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (192 ÷ 240) × 100% = 80%.
5. 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%.
6. A machine is supplied with 40 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (20 ÷ 40) × 100% = 50%.
7. A machine is supplied with 440 J of total energy and transfers 110 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (110 ÷ 440) × 100% = 25%.
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 80 J of total energy and transfers 16 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (16 ÷ 80) × 100% = 20%.
10. A machine is supplied with 460 J of total energy and transfers 414 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (414 ÷ 460) × 100% = 90%.
11. 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%.
12. A machine is supplied with 380 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (323 ÷ 380) × 100% = 85%.

12 questions · Seed 104740 · 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 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 64 J · Wasted: 96 J
2. A machine is supplied with 380 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 57 J · Wasted: 323 J
3. A machine is supplied with 180 J of total energy and transfers 135 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 135 J · Wasted: 45 J
4. A machine is supplied with 240 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 192 J · Wasted: 48 J
5. 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
6. A machine is supplied with 40 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 20 J · Wasted: 20 J
7. A machine is supplied with 440 J of total energy and transfers 110 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 110 J · Wasted: 330 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 80 J of total energy and transfers 16 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 16 J · Wasted: 64 J
10. A machine is supplied with 460 J of total energy and transfers 414 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 414 J · Wasted: 46 J
11. 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
12. A machine is supplied with 380 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 323 J · Wasted: 57 J

12 questions · Seed 104740 · 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 160 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 160) × 100% = 40%.
2. A machine is supplied with 380 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 380) × 100% = 15%.
3. A machine is supplied with 180 J of total energy and transfers 135 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (135 ÷ 180) × 100% = 75%.
4. A machine is supplied with 240 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (192 ÷ 240) × 100% = 80%.
5. 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%.
6. A machine is supplied with 40 J of total energy and transfers 20 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (20 ÷ 40) × 100% = 50%.
7. A machine is supplied with 440 J of total energy and transfers 110 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (110 ÷ 440) × 100% = 25%.
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 80 J of total energy and transfers 16 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (16 ÷ 80) × 100% = 20%.
10. A machine is supplied with 460 J of total energy and transfers 414 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (414 ÷ 460) × 100% = 90%.
11. 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%.
12. A machine is supplied with 380 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (323 ÷ 380) × 100% = 85%.

12 questions · Seed 104740 · Age guidance, not curriculum certification