ScienceAges 13-15

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 13-15

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 120 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 36 J · Wasted: 84 J
2. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 48 J · Wasted: 72 J
3. A machine is supplied with 140 J of total energy and transfers 35 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 35 J · Wasted: 105 J
4. A machine is supplied with 40 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 32 J · Wasted: 8 J
5. A machine is supplied with 260 J of total energy and transfers 65 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 65 J · Wasted: 195 J
6. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 126 J · Wasted: 14 J
7. A machine is supplied with 260 J of total energy and transfers 104 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 104 J · Wasted: 156 J
8. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 84 J · Wasted: 196 J
9. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 136 J · Wasted: 24 J
10. A machine is supplied with 40 J of total energy and transfers 34 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 34 J · Wasted: 6 J
11. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 108 J · Wasted: 252 J
12. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 60 J · Wasted: 20 J

12 questions · Seed 46 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 13-15

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 120 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 120) × 100% = 30%.
2. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 120) × 100% = 40%.
3. A machine is supplied with 140 J of total energy and transfers 35 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (35 ÷ 140) × 100% = 25%.
4. A machine is supplied with 40 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (32 ÷ 40) × 100% = 80%.
5. A machine is supplied with 260 J of total energy and transfers 65 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (65 ÷ 260) × 100% = 25%.
6. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (126 ÷ 140) × 100% = 90%.
7. A machine is supplied with 260 J of total energy and transfers 104 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (104 ÷ 260) × 100% = 40%.
8. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (84 ÷ 280) × 100% = 30%.
9. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (136 ÷ 160) × 100% = 85%.
10. A machine is supplied with 40 J of total energy and transfers 34 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (34 ÷ 40) × 100% = 85%.
11. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (108 ÷ 360) × 100% = 30%.
12. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (60 ÷ 80) × 100% = 75%.

12 questions · Seed 46 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 13-15

Percentage energy efficiency

Take your time. Show your thinking.

1. A machine is supplied with 120 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 36 J · Wasted: 84 J
2. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 48 J · Wasted: 72 J
3. A machine is supplied with 140 J of total energy and transfers 35 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 35 J · Wasted: 105 J
4. A machine is supplied with 40 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 32 J · Wasted: 8 J
5. A machine is supplied with 260 J of total energy and transfers 65 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 65 J · Wasted: 195 J
6. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 126 J · Wasted: 14 J
7. A machine is supplied with 260 J of total energy and transfers 104 J as useful energy output. Calculate its percentage efficiency.
In: 260 J → Useful: 104 J · Wasted: 156 J
8. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 84 J · Wasted: 196 J
9. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 136 J · Wasted: 24 J
10. A machine is supplied with 40 J of total energy and transfers 34 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 34 J · Wasted: 6 J
11. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 108 J · Wasted: 252 J
12. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 60 J · Wasted: 20 J

12 questions · Seed 46 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 13-15

Percentage energy efficiency

Answers and reasoning. Review before teaching.

1. A machine is supplied with 120 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 120) × 100% = 30%.
2. A machine is supplied with 120 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 120) × 100% = 40%.
3. A machine is supplied with 140 J of total energy and transfers 35 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (35 ÷ 140) × 100% = 25%.
4. A machine is supplied with 40 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (32 ÷ 40) × 100% = 80%.
5. A machine is supplied with 260 J of total energy and transfers 65 J as useful energy output. Calculate its percentage efficiency.
25%
Efficiency = (useful energy output ÷ total energy input) × 100% = (65 ÷ 260) × 100% = 25%.
6. A machine is supplied with 140 J of total energy and transfers 126 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (126 ÷ 140) × 100% = 90%.
7. A machine is supplied with 260 J of total energy and transfers 104 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (104 ÷ 260) × 100% = 40%.
8. A machine is supplied with 280 J of total energy and transfers 84 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (84 ÷ 280) × 100% = 30%.
9. A machine is supplied with 160 J of total energy and transfers 136 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (136 ÷ 160) × 100% = 85%.
10. A machine is supplied with 40 J of total energy and transfers 34 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (34 ÷ 40) × 100% = 85%.
11. A machine is supplied with 360 J of total energy and transfers 108 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (108 ÷ 360) × 100% = 30%.
12. A machine is supplied with 80 J of total energy and transfers 60 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (60 ÷ 80) × 100% = 75%.

12 questions · Seed 46 · Age guidance, not curriculum certification