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 320 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 48 J · Wasted: 272 J
2. A machine is supplied with 420 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 105 J · Wasted: 315 J
3. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 221 J · Wasted: 39 J
4. 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
5. A machine is supplied with 60 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 48 J · Wasted: 12 J
6. A machine is supplied with 200 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 30 J · Wasted: 170 J
7. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 105 J · Wasted: 35 J
8. A machine is supplied with 160 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 144 J · Wasted: 16 J
9. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 252 J · Wasted: 28 J
10. A machine is supplied with 360 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 306 J · Wasted: 54 J
11. A machine is supplied with 420 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 84 J · Wasted: 336 J
12. A machine is supplied with 340 J of total energy and transfers 68 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 68 J · Wasted: 272 J

12 questions · Seed 45 · 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 320 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 320) × 100% = 15%.
2. A machine is supplied with 420 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (105 ÷ 420) × 100% = 25%.
3. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (221 ÷ 260) × 100% = 85%.
4. 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%.
5. A machine is supplied with 60 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 60) × 100% = 80%.
6. A machine is supplied with 200 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 200) × 100% = 15%.
7. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (105 ÷ 140) × 100% = 75%.
8. A machine is supplied with 160 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 160) × 100% = 90%.
9. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (252 ÷ 280) × 100% = 90%.
10. A machine is supplied with 360 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (306 ÷ 360) × 100% = 85%.
11. A machine is supplied with 420 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (84 ÷ 420) × 100% = 20%.
12. A machine is supplied with 340 J of total energy and transfers 68 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (68 ÷ 340) × 100% = 20%.

12 questions · Seed 45 · 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 320 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 48 J · Wasted: 272 J
2. A machine is supplied with 420 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 105 J · Wasted: 315 J
3. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 221 J · Wasted: 39 J
4. 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
5. A machine is supplied with 60 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 48 J · Wasted: 12 J
6. A machine is supplied with 200 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 30 J · Wasted: 170 J
7. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 105 J · Wasted: 35 J
8. A machine is supplied with 160 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 144 J · Wasted: 16 J
9. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 252 J · Wasted: 28 J
10. A machine is supplied with 360 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 306 J · Wasted: 54 J
11. A machine is supplied with 420 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 84 J · Wasted: 336 J
12. A machine is supplied with 340 J of total energy and transfers 68 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 68 J · Wasted: 272 J

12 questions · Seed 45 · 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 320 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 320) × 100% = 15%.
2. A machine is supplied with 420 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (105 ÷ 420) × 100% = 25%.
3. A machine is supplied with 260 J of total energy and transfers 221 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (221 ÷ 260) × 100% = 85%.
4. 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%.
5. A machine is supplied with 60 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 60) × 100% = 80%.
6. A machine is supplied with 200 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
15%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 200) × 100% = 15%.
7. A machine is supplied with 140 J of total energy and transfers 105 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (105 ÷ 140) × 100% = 75%.
8. A machine is supplied with 160 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 160) × 100% = 90%.
9. A machine is supplied with 280 J of total energy and transfers 252 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (252 ÷ 280) × 100% = 90%.
10. A machine is supplied with 360 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (306 ÷ 360) × 100% = 85%.
11. A machine is supplied with 420 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (84 ÷ 420) × 100% = 20%.
12. A machine is supplied with 340 J of total energy and transfers 68 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (68 ÷ 340) × 100% = 20%.

12 questions · Seed 45 · Age guidance, not curriculum certification