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 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 153 J · Wasted: 27 J
2. 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
3. A machine is supplied with 260 J of total energy and transfers 52 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 52 J · Wasted: 208 J
4. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 152 J · Wasted: 8 J
5. A machine is supplied with 340 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 323 J · Wasted: 17 J
6. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 50 J · Wasted: 150 J
7. A machine is supplied with 180 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 45 J · Wasted: 135 J
8. A machine is supplied with 220 J of total energy and transfers 187 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 187 J · Wasted: 33 J
9. A machine is supplied with 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 130 J · Wasted: 130 J
10. A machine is supplied with 140 J of total energy and transfers 133 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 133 J · Wasted: 7 J
11. 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
12. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 234 J · Wasted: 26 J

12 questions · Seed 104741 · 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 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (153 ÷ 180) × 100% = 85%.
2. 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%.
3. A machine is supplied with 260 J of total energy and transfers 52 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (52 ÷ 260) × 100% = 20%.
4. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (152 ÷ 160) × 100% = 95%.
5. A machine is supplied with 340 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (323 ÷ 340) × 100% = 95%.
6. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (50 ÷ 200) × 100% = 25%.
7. A machine is supplied with 180 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (45 ÷ 180) × 100% = 25%.
8. A machine is supplied with 220 J of total energy and transfers 187 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (187 ÷ 220) × 100% = 85%.
9. A machine is supplied with 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (130 ÷ 260) × 100% = 50%.
10. A machine is supplied with 140 J of total energy and transfers 133 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (133 ÷ 140) × 100% = 95%.
11. 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%.
12. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (234 ÷ 260) × 100% = 90%.

12 questions · Seed 104741 · 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 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 153 J · Wasted: 27 J
2. 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
3. A machine is supplied with 260 J of total energy and transfers 52 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 52 J · Wasted: 208 J
4. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 152 J · Wasted: 8 J
5. A machine is supplied with 340 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 323 J · Wasted: 17 J
6. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 50 J · Wasted: 150 J
7. A machine is supplied with 180 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 45 J · Wasted: 135 J
8. A machine is supplied with 220 J of total energy and transfers 187 J as useful energy output. Calculate its percentage efficiency.
In: 220 J → Useful: 187 J · Wasted: 33 J
9. A machine is supplied with 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 130 J · Wasted: 130 J
10. A machine is supplied with 140 J of total energy and transfers 133 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 133 J · Wasted: 7 J
11. 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
12. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 234 J · Wasted: 26 J

12 questions · Seed 104741 · 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 180 J of total energy and transfers 153 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (153 ÷ 180) × 100% = 85%.
2. 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%.
3. A machine is supplied with 260 J of total energy and transfers 52 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (52 ÷ 260) × 100% = 20%.
4. A machine is supplied with 160 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (152 ÷ 160) × 100% = 95%.
5. A machine is supplied with 340 J of total energy and transfers 323 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (323 ÷ 340) × 100% = 95%.
6. A machine is supplied with 200 J of total energy and transfers 50 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (50 ÷ 200) × 100% = 25%.
7. A machine is supplied with 180 J of total energy and transfers 45 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (45 ÷ 180) × 100% = 25%.
8. A machine is supplied with 220 J of total energy and transfers 187 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (187 ÷ 220) × 100% = 85%.
9. A machine is supplied with 260 J of total energy and transfers 130 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (130 ÷ 260) × 100% = 50%.
10. A machine is supplied with 140 J of total energy and transfers 133 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (133 ÷ 140) × 100% = 95%.
11. 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%.
12. A machine is supplied with 260 J of total energy and transfers 234 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (234 ÷ 260) × 100% = 90%.

12 questions · Seed 104741 · Age guidance, not curriculum certification