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 160 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 72 J · Wasted: 88 J
2. A machine is supplied with 340 J of total energy and transfers 255 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 255 J · Wasted: 85 J
3. A machine is supplied with 40 J of total energy and transfers 10 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 10 J · Wasted: 30 J
4. A machine is supplied with 320 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 64 J · Wasted: 256 J
5. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 112 J · Wasted: 168 J
6. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 437 J · Wasted: 23 J
7. 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
8. 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
9. A machine is supplied with 180 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 54 J · Wasted: 126 J
10. A machine is supplied with 400 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 120 J · Wasted: 280 J
11. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 57 J · Wasted: 3 J
12. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 125 J · Wasted: 375 J

12 questions · Seed 104737 · 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 160 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 160) × 100% = 45%.
2. A machine is supplied with 340 J of total energy and transfers 255 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (255 ÷ 340) × 100% = 75%.
3. A machine is supplied with 40 J of total energy and transfers 10 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (10 ÷ 40) × 100% = 25%.
4. A machine is supplied with 320 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 320) × 100% = 20%.
5. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 280) × 100% = 40%.
6. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (437 ÷ 460) × 100% = 95%.
7. 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%.
8. 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%.
9. A machine is supplied with 180 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (54 ÷ 180) × 100% = 30%.
10. A machine is supplied with 400 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (120 ÷ 400) × 100% = 30%.
11. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 60) × 100% = 95%.
12. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (125 ÷ 500) × 100% = 25%.

12 questions · Seed 104737 · 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 160 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 72 J · Wasted: 88 J
2. A machine is supplied with 340 J of total energy and transfers 255 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 255 J · Wasted: 85 J
3. A machine is supplied with 40 J of total energy and transfers 10 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 10 J · Wasted: 30 J
4. A machine is supplied with 320 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 64 J · Wasted: 256 J
5. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 112 J · Wasted: 168 J
6. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 437 J · Wasted: 23 J
7. 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
8. 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
9. A machine is supplied with 180 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 54 J · Wasted: 126 J
10. A machine is supplied with 400 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 120 J · Wasted: 280 J
11. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 57 J · Wasted: 3 J
12. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 125 J · Wasted: 375 J

12 questions · Seed 104737 · 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 160 J of total energy and transfers 72 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (72 ÷ 160) × 100% = 45%.
2. A machine is supplied with 340 J of total energy and transfers 255 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (255 ÷ 340) × 100% = 75%.
3. A machine is supplied with 40 J of total energy and transfers 10 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (10 ÷ 40) × 100% = 25%.
4. A machine is supplied with 320 J of total energy and transfers 64 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (64 ÷ 320) × 100% = 20%.
5. A machine is supplied with 280 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 280) × 100% = 40%.
6. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (437 ÷ 460) × 100% = 95%.
7. 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%.
8. 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%.
9. A machine is supplied with 180 J of total energy and transfers 54 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (54 ÷ 180) × 100% = 30%.
10. A machine is supplied with 400 J of total energy and transfers 120 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (120 ÷ 400) × 100% = 30%.
11. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 60) × 100% = 95%.
12. A machine is supplied with 500 J of total energy and transfers 125 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (125 ÷ 500) × 100% = 25%.

12 questions · Seed 104737 · Age guidance, not curriculum certification