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 360 J of total energy and transfers 162 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 162 J · Wasted: 198 J
2. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 119 J · Wasted: 221 J
3. A machine is supplied with 120 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 54 J · Wasted: 66 J
4. A machine is supplied with 200 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 100 J · Wasted: 100 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 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 176 J · Wasted: 264 J
7. A machine is supplied with 460 J of total energy and transfers 161 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 161 J · Wasted: 299 J
8. A machine is supplied with 500 J of total energy and transfers 225 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 225 J · Wasted: 275 J
9. 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
10. A machine is supplied with 120 J of total energy and transfers 24 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 24 J · Wasted: 96 J
11. A machine is supplied with 360 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 90 J · Wasted: 270 J
12. A machine is supplied with 220 J of total energy and transfers 165 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 165 J · Wasted: 55 J

12 questions · Seed 104745 · 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 360 J of total energy and transfers 162 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (162 ÷ 360) × 100% = 45%.
2. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (119 ÷ 340) × 100% = 35%.
3. A machine is supplied with 120 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (54 ÷ 120) × 100% = 45%.
4. A machine is supplied with 200 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (100 ÷ 200) × 100% = 50%.
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 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (176 ÷ 440) × 100% = 40%.
7. A machine is supplied with 460 J of total energy and transfers 161 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (161 ÷ 460) × 100% = 35%.
8. A machine is supplied with 500 J of total energy and transfers 225 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (225 ÷ 500) × 100% = 45%.
9. 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%.
10. A machine is supplied with 120 J of total energy and transfers 24 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (24 ÷ 120) × 100% = 20%.
11. A machine is supplied with 360 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 360) × 100% = 25%.
12. A machine is supplied with 220 J of total energy and transfers 165 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (165 ÷ 220) × 100% = 75%.

12 questions · Seed 104745 · 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 360 J of total energy and transfers 162 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 162 J · Wasted: 198 J
2. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 119 J · Wasted: 221 J
3. A machine is supplied with 120 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 54 J · Wasted: 66 J
4. A machine is supplied with 200 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 100 J · Wasted: 100 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 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 176 J · Wasted: 264 J
7. A machine is supplied with 460 J of total energy and transfers 161 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 161 J · Wasted: 299 J
8. A machine is supplied with 500 J of total energy and transfers 225 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 225 J · Wasted: 275 J
9. 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
10. A machine is supplied with 120 J of total energy and transfers 24 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 24 J · Wasted: 96 J
11. A machine is supplied with 360 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 90 J · Wasted: 270 J
12. A machine is supplied with 220 J of total energy and transfers 165 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 165 J · Wasted: 55 J

12 questions · Seed 104745 · 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 360 J of total energy and transfers 162 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (162 ÷ 360) × 100% = 45%.
2. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (119 ÷ 340) × 100% = 35%.
3. A machine is supplied with 120 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (54 ÷ 120) × 100% = 45%.
4. A machine is supplied with 200 J of total energy and transfers 100 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (100 ÷ 200) × 100% = 50%.
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 440 J of total energy and transfers 176 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (176 ÷ 440) × 100% = 40%.
7. A machine is supplied with 460 J of total energy and transfers 161 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (161 ÷ 460) × 100% = 35%.
8. A machine is supplied with 500 J of total energy and transfers 225 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (225 ÷ 500) × 100% = 45%.
9. 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%.
10. A machine is supplied with 120 J of total energy and transfers 24 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (24 ÷ 120) × 100% = 20%.
11. A machine is supplied with 360 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 360) × 100% = 25%.
12. A machine is supplied with 220 J of total energy and transfers 165 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (165 ÷ 220) × 100% = 75%.

12 questions · Seed 104745 · Age guidance, not curriculum certification