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 200 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 80 J · Wasted: 120 J
2. A machine is supplied with 420 J of total energy and transfers 357 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 357 J · Wasted: 63 J
3. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 216 J · Wasted: 264 J
4. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 49 J · Wasted: 91 J
5. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 112 J · Wasted: 28 J
6. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 51 J · Wasted: 9 J
7. A machine is supplied with 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 88 J · Wasted: 352 J
8. A machine is supplied with 260 J of total energy and transfers 247 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 247 J · Wasted: 13 J
9. A machine is supplied with 320 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 160 J · Wasted: 160 J
10. A machine is supplied with 460 J of total energy and transfers 345 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 345 J · Wasted: 115 J
11. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 144 J · Wasted: 216 J
12. A machine is supplied with 480 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 96 J · Wasted: 384 J

12 questions · Seed 104739 · 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 200 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 200) × 100% = 40%.
2. A machine is supplied with 420 J of total energy and transfers 357 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (357 ÷ 420) × 100% = 85%.
3. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (216 ÷ 480) × 100% = 45%.
4. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (49 ÷ 140) × 100% = 35%.
5. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 140) × 100% = 80%.
6. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (51 ÷ 60) × 100% = 85%.
7. A machine is supplied with 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (88 ÷ 440) × 100% = 20%.
8. A machine is supplied with 260 J of total energy and transfers 247 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (247 ÷ 260) × 100% = 95%.
9. A machine is supplied with 320 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 320) × 100% = 50%.
10. A machine is supplied with 460 J of total energy and transfers 345 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (345 ÷ 460) × 100% = 75%.
11. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 360) × 100% = 40%.
12. A machine is supplied with 480 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (96 ÷ 480) × 100% = 20%.

12 questions · Seed 104739 · 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 200 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 80 J · Wasted: 120 J
2. A machine is supplied with 420 J of total energy and transfers 357 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 357 J · Wasted: 63 J
3. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 216 J · Wasted: 264 J
4. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 49 J · Wasted: 91 J
5. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 112 J · Wasted: 28 J
6. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 51 J · Wasted: 9 J
7. A machine is supplied with 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
In: 440 J → Useful: 88 J · Wasted: 352 J
8. A machine is supplied with 260 J of total energy and transfers 247 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 247 J · Wasted: 13 J
9. A machine is supplied with 320 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 160 J · Wasted: 160 J
10. A machine is supplied with 460 J of total energy and transfers 345 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 345 J · Wasted: 115 J
11. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 144 J · Wasted: 216 J
12. A machine is supplied with 480 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 96 J · Wasted: 384 J

12 questions · Seed 104739 · 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 200 J of total energy and transfers 80 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (80 ÷ 200) × 100% = 40%.
2. A machine is supplied with 420 J of total energy and transfers 357 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (357 ÷ 420) × 100% = 85%.
3. A machine is supplied with 480 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (216 ÷ 480) × 100% = 45%.
4. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (49 ÷ 140) × 100% = 35%.
5. A machine is supplied with 140 J of total energy and transfers 112 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (112 ÷ 140) × 100% = 80%.
6. A machine is supplied with 60 J of total energy and transfers 51 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (51 ÷ 60) × 100% = 85%.
7. A machine is supplied with 440 J of total energy and transfers 88 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (88 ÷ 440) × 100% = 20%.
8. A machine is supplied with 260 J of total energy and transfers 247 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (247 ÷ 260) × 100% = 95%.
9. A machine is supplied with 320 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 320) × 100% = 50%.
10. A machine is supplied with 460 J of total energy and transfers 345 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (345 ÷ 460) × 100% = 75%.
11. A machine is supplied with 360 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 360) × 100% = 40%.
12. A machine is supplied with 480 J of total energy and transfers 96 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (96 ÷ 480) × 100% = 20%.

12 questions · Seed 104739 · Age guidance, not curriculum certification