ScienceAges 13-15

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 13-15

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 400 J of total energy and transfers 200 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 200 J · Wasted: 200 J
2. 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
3. A machine is supplied with 320 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 80 J · Wasted: 240 J
4. A machine is supplied with 20 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 15 J · Wasted: 5 J
5. A machine is supplied with 260 J of total energy and transfers 78 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 78 J · Wasted: 182 J
6. A machine is supplied with 220 J of total energy and transfers 66 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 66 J · Wasted: 154 J
7. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 56 J · Wasted: 104 J
8. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 75 J · Wasted: 425 J
9. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 270 J · Wasted: 30 J
10. A machine is supplied with 420 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 252 J · Wasted: 168 J
11. A machine is supplied with 320 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 192 J · Wasted: 128 J
12. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 72 J · Wasted: 48 J

12 questions · Seed 49 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 13-15

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 400 J of total energy and transfers 200 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (200 ÷ 400) × 100% = 50%.
2. 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%.
3. A machine is supplied with 320 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 320) × 100% = 25%.
4. A machine is supplied with 20 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (15 ÷ 20) × 100% = 75%.
5. A machine is supplied with 260 J of total energy and transfers 78 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (78 ÷ 260) × 100% = 30%.
6. A machine is supplied with 220 J of total energy and transfers 66 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (66 ÷ 220) × 100% = 30%.
7. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (56 ÷ 160) × 100% = 35%.
8. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (75 ÷ 500) × 100% = 15%.
9. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (270 ÷ 300) × 100% = 90%.
10. A machine is supplied with 420 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (252 ÷ 420) × 100% = 60%.
11. A machine is supplied with 320 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (192 ÷ 320) × 100% = 60%.
12. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 120) × 100% = 60%.

12 questions · Seed 49 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 13-15

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 400 J of total energy and transfers 200 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 200 J · Wasted: 200 J
2. 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
3. A machine is supplied with 320 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 80 J · Wasted: 240 J
4. A machine is supplied with 20 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 15 J · Wasted: 5 J
5. A machine is supplied with 260 J of total energy and transfers 78 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 78 J · Wasted: 182 J
6. A machine is supplied with 220 J of total energy and transfers 66 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 66 J · Wasted: 154 J
7. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 56 J · Wasted: 104 J
8. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 75 J · Wasted: 425 J
9. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
In: 300 J → Useful: 270 J · Wasted: 30 J
10. A machine is supplied with 420 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 252 J · Wasted: 168 J
11. A machine is supplied with 320 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 192 J · Wasted: 128 J
12. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 72 J · Wasted: 48 J

12 questions · Seed 49 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 13-15

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 400 J of total energy and transfers 200 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (200 ÷ 400) × 100% = 50%.
2. 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%.
3. A machine is supplied with 320 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 320) × 100% = 25%.
4. A machine is supplied with 20 J of total energy and transfers 15 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (15 ÷ 20) × 100% = 75%.
5. A machine is supplied with 260 J of total energy and transfers 78 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (78 ÷ 260) × 100% = 30%.
6. A machine is supplied with 220 J of total energy and transfers 66 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (66 ÷ 220) × 100% = 30%.
7. A machine is supplied with 160 J of total energy and transfers 56 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (56 ÷ 160) × 100% = 35%.
8. A machine is supplied with 500 J of total energy and transfers 75 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (75 ÷ 500) × 100% = 15%.
9. A machine is supplied with 300 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (270 ÷ 300) × 100% = 90%.
10. A machine is supplied with 420 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (252 ÷ 420) × 100% = 60%.
11. A machine is supplied with 320 J of total energy and transfers 192 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (192 ÷ 320) × 100% = 60%.
12. A machine is supplied with 120 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 120) × 100% = 60%.

12 questions · Seed 49 · Age guidance, not curriculum certification