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 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 130 J · Wasted: 130 J
2. A machine is supplied with 160 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 80 J · Wasted: 80 J
3. A machine is supplied with 480 J of total energy and transfers 384 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 384 J · Wasted: 96 J
4. A machine is supplied with 220 J of total energy and transfers 99 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 99 J · Wasted: 121 J
5. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 136 J · Wasted: 24 J
6. A machine is supplied with 40 J of total energy and transfers 38 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 38 J · Wasted: 2 J
7. A machine is supplied with 20 J of total energy and transfers 7 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 7 J · Wasted: 13 J
8. A machine is supplied with 120 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 30 J · Wasted: 90 J
9. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 50 J · Wasted: 150 J
10. 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
11. 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
12. A machine is supplied with 500 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 300 J · Wasted: 200 J

12 questions · Seed 47 · 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 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (130 ÷ 260) × 100% = 50%.
2. A machine is supplied with 160 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 160) × 100% = 50%.
3. A machine is supplied with 480 J of total energy and transfers 384 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (384 ÷ 480) × 100% = 80%.
4. A machine is supplied with 220 J of total energy and transfers 99 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (99 ÷ 220) × 100% = 45%.
5. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (136 ÷ 160) × 100% = 85%.
6. A machine is supplied with 40 J of total energy and transfers 38 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (38 ÷ 40) × 100% = 95%.
7. A machine is supplied with 20 J of total energy and transfers 7 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (7 ÷ 20) × 100% = 35%.
8. A machine is supplied with 120 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 120) × 100% = 25%.
9. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (50 ÷ 200) × 100% = 25%.
10. 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%.
11. 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%.
12. A machine is supplied with 500 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (300 ÷ 500) × 100% = 60%.

12 questions · Seed 47 · 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 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 130 J · Wasted: 130 J
2. A machine is supplied with 160 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 80 J · Wasted: 80 J
3. A machine is supplied with 480 J of total energy and transfers 384 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 384 J · Wasted: 96 J
4. A machine is supplied with 220 J of total energy and transfers 99 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 99 J · Wasted: 121 J
5. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 136 J · Wasted: 24 J
6. A machine is supplied with 40 J of total energy and transfers 38 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 38 J · Wasted: 2 J
7. A machine is supplied with 20 J of total energy and transfers 7 J as useful energy output. Calculate its percentage efficiency.
In: 20 J → Useful: 7 J · Wasted: 13 J
8. A machine is supplied with 120 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 30 J · Wasted: 90 J
9. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 50 J · Wasted: 150 J
10. 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
11. 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
12. A machine is supplied with 500 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 300 J · Wasted: 200 J

12 questions · Seed 47 · 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 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (130 ÷ 260) × 100% = 50%.
2. A machine is supplied with 160 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 160) × 100% = 50%.
3. A machine is supplied with 480 J of total energy and transfers 384 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (384 ÷ 480) × 100% = 80%.
4. A machine is supplied with 220 J of total energy and transfers 99 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (99 ÷ 220) × 100% = 45%.
5. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (136 ÷ 160) × 100% = 85%.
6. A machine is supplied with 40 J of total energy and transfers 38 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (38 ÷ 40) × 100% = 95%.
7. A machine is supplied with 20 J of total energy and transfers 7 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (7 ÷ 20) × 100% = 35%.
8. A machine is supplied with 120 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 120) × 100% = 25%.
9. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (50 ÷ 200) × 100% = 25%.
10. 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%.
11. 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%.
12. A machine is supplied with 500 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (300 ÷ 500) × 100% = 60%.

12 questions · Seed 47 · Age guidance, not curriculum certification