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 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 6 J · Wasted: 34 J
2. A machine is supplied with 240 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 120 J · Wasted: 120 J
3. A machine is supplied with 40 J of total energy and transfers 12 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 12 J · Wasted: 28 J
4. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 216 J · Wasted: 264 J
5. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 57 J · Wasted: 3 J
6. A machine is supplied with 340 J of total energy and transfers 289 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 289 J · Wasted: 51 J
7. A machine is supplied with 460 J of total energy and transfers 69 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 69 J · Wasted: 391 J
8. A machine is supplied with 160 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 120 J · Wasted: 40 J
9. 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
10. 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
11. A machine is supplied with 440 J of total energy and transfers 396 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 396 J · Wasted: 44 J
12. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 252 J · Wasted: 28 J

12 questions · Seed 104734 · 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 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (6 ÷ 40) × 100% = 15%.
2. A machine is supplied with 240 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (120 ÷ 240) × 100% = 50%.
3. A machine is supplied with 40 J of total energy and transfers 12 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (12 ÷ 40) × 100% = 30%.
4. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (216 ÷ 480) × 100% = 45%.
5. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 60) × 100% = 95%.
6. A machine is supplied with 340 J of total energy and transfers 289 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (289 ÷ 340) × 100% = 85%.
7. A machine is supplied with 460 J of total energy and transfers 69 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (69 ÷ 460) × 100% = 15%.
8. A machine is supplied with 160 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (120 ÷ 160) × 100% = 75%.
9. 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%.
10. 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%.
11. A machine is supplied with 440 J of total energy and transfers 396 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (396 ÷ 440) × 100% = 90%.
12. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (252 ÷ 280) × 100% = 90%.

12 questions · Seed 104734 · 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 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 6 J · Wasted: 34 J
2. A machine is supplied with 240 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 120 J · Wasted: 120 J
3. A machine is supplied with 40 J of total energy and transfers 12 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 12 J · Wasted: 28 J
4. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 216 J · Wasted: 264 J
5. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 57 J · Wasted: 3 J
6. A machine is supplied with 340 J of total energy and transfers 289 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 289 J · Wasted: 51 J
7. A machine is supplied with 460 J of total energy and transfers 69 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 69 J · Wasted: 391 J
8. A machine is supplied with 160 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 120 J · Wasted: 40 J
9. 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
10. 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
11. A machine is supplied with 440 J of total energy and transfers 396 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 396 J · Wasted: 44 J
12. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 252 J · Wasted: 28 J

12 questions · Seed 104734 · 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 40 J of total energy and transfers 6 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (6 ÷ 40) × 100% = 15%.
2. A machine is supplied with 240 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (120 ÷ 240) × 100% = 50%.
3. A machine is supplied with 40 J of total energy and transfers 12 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (12 ÷ 40) × 100% = 30%.
4. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (216 ÷ 480) × 100% = 45%.
5. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 60) × 100% = 95%.
6. A machine is supplied with 340 J of total energy and transfers 289 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (289 ÷ 340) × 100% = 85%.
7. A machine is supplied with 460 J of total energy and transfers 69 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (69 ÷ 460) × 100% = 15%.
8. A machine is supplied with 160 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (120 ÷ 160) × 100% = 75%.
9. 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%.
10. 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%.
11. A machine is supplied with 440 J of total energy and transfers 396 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (396 ÷ 440) × 100% = 90%.
12. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (252 ÷ 280) × 100% = 90%.

12 questions · Seed 104734 · Age guidance, not curriculum certification