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 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
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 160 J · Wasted: 240 J
3. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 63 J · Wasted: 77 J
4. A machine is supplied with 120 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 90 J · Wasted: 30 J
5. 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
6. A machine is supplied with 440 J of total energy and transfers 154 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 154 J · Wasted: 286 J
7. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 224 J · Wasted: 56 J
8. 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
9. 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
10. A machine is supplied with 100 J of total energy and transfers 85 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 85 J · Wasted: 15 J
11. A machine is supplied with 380 J of total energy and transfers 190 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 190 J · Wasted: 190 J
12. A machine is supplied with 400 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 180 J · Wasted: 220 J

12 questions · Seed 104733 · 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 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%.
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 400) × 100% = 40%.
3. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (63 ÷ 140) × 100% = 45%.
4. A machine is supplied with 120 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 120) × 100% = 75%.
5. 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%.
6. A machine is supplied with 440 J of total energy and transfers 154 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (154 ÷ 440) × 100% = 35%.
7. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (224 ÷ 280) × 100% = 80%.
8. 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%.
9. 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%.
10. A machine is supplied with 100 J of total energy and transfers 85 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (85 ÷ 100) × 100% = 85%.
11. A machine is supplied with 380 J of total energy and transfers 190 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (190 ÷ 380) × 100% = 50%.
12. A machine is supplied with 400 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (180 ÷ 400) × 100% = 45%.

12 questions · Seed 104733 · 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 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
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 160 J · Wasted: 240 J
3. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 63 J · Wasted: 77 J
4. A machine is supplied with 120 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 90 J · Wasted: 30 J
5. 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
6. A machine is supplied with 440 J of total energy and transfers 154 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 154 J · Wasted: 286 J
7. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 224 J · Wasted: 56 J
8. 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
9. 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
10. A machine is supplied with 100 J of total energy and transfers 85 J as useful energy output. Calculate its percentage efficiency.
In: 100 J → Useful: 85 J · Wasted: 15 J
11. A machine is supplied with 380 J of total energy and transfers 190 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 190 J · Wasted: 190 J
12. A machine is supplied with 400 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 180 J · Wasted: 220 J

12 questions · Seed 104733 · 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 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%.
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 400) × 100% = 40%.
3. A machine is supplied with 140 J of total energy and transfers 63 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (63 ÷ 140) × 100% = 45%.
4. A machine is supplied with 120 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 120) × 100% = 75%.
5. 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%.
6. A machine is supplied with 440 J of total energy and transfers 154 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (154 ÷ 440) × 100% = 35%.
7. A machine is supplied with 280 J of total energy and transfers 224 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (224 ÷ 280) × 100% = 80%.
8. 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%.
9. 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%.
10. A machine is supplied with 100 J of total energy and transfers 85 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (85 ÷ 100) × 100% = 85%.
11. A machine is supplied with 380 J of total energy and transfers 190 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (190 ÷ 380) × 100% = 50%.
12. A machine is supplied with 400 J of total energy and transfers 180 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (180 ÷ 400) × 100% = 45%.

12 questions · Seed 104733 · Age guidance, not curriculum certification