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 460 J of total energy and transfers 391 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 391 J · Wasted: 69 J
2. 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
3. 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
4. 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
5. A machine is supplied with 320 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 240 J · Wasted: 80 J
6. A machine is supplied with 420 J of total energy and transfers 378 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 378 J · Wasted: 42 J
7. 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
8. A machine is supplied with 240 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 96 J · Wasted: 144 J
9. 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
10. A machine is supplied with 400 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 300 J · Wasted: 100 J
11. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 48 J · Wasted: 112 J
12. A machine is supplied with 60 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 36 J · Wasted: 24 J

12 questions · Seed 104744 · 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 460 J of total energy and transfers 391 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (391 ÷ 460) × 100% = 85%.
2. 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%.
3. 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%.
4. 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%.
5. A machine is supplied with 320 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 320) × 100% = 75%.
6. A machine is supplied with 420 J of total energy and transfers 378 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (378 ÷ 420) × 100% = 90%.
7. 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%.
8. A machine is supplied with 240 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (96 ÷ 240) × 100% = 40%.
9. 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%.
10. A machine is supplied with 400 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (300 ÷ 400) × 100% = 75%.
11. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 160) × 100% = 30%.
12. A machine is supplied with 60 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 60) × 100% = 60%.

12 questions · Seed 104744 · 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 460 J of total energy and transfers 391 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 391 J · Wasted: 69 J
2. 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
3. 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
4. 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
5. A machine is supplied with 320 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 240 J · Wasted: 80 J
6. A machine is supplied with 420 J of total energy and transfers 378 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 378 J · Wasted: 42 J
7. 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
8. A machine is supplied with 240 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 96 J · Wasted: 144 J
9. 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
10. A machine is supplied with 400 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 300 J · Wasted: 100 J
11. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 48 J · Wasted: 112 J
12. A machine is supplied with 60 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 36 J · Wasted: 24 J

12 questions · Seed 104744 · 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 460 J of total energy and transfers 391 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (391 ÷ 460) × 100% = 85%.
2. 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%.
3. 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%.
4. 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%.
5. A machine is supplied with 320 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 320) × 100% = 75%.
6. A machine is supplied with 420 J of total energy and transfers 378 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (378 ÷ 420) × 100% = 90%.
7. 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%.
8. A machine is supplied with 240 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (96 ÷ 240) × 100% = 40%.
9. 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%.
10. A machine is supplied with 400 J of total energy and transfers 300 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (300 ÷ 400) × 100% = 75%.
11. A machine is supplied with 160 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 160) × 100% = 30%.
12. A machine is supplied with 60 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
60%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 60) × 100% = 60%.

12 questions · Seed 104744 · Age guidance, not curriculum certification