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 360 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 270 J · Wasted: 90 J
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 160 J · Wasted: 240 J
3. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 42 J · Wasted: 78 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 500 J of total energy and transfers 475 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 475 J · Wasted: 25 J
6. A machine is supplied with 200 J of total energy and transfers 170 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 170 J · Wasted: 30 J
7. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 144 J · Wasted: 36 J
8. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 119 J · Wasted: 221 J
9. A machine is supplied with 420 J of total energy and transfers 315 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 315 J · Wasted: 105 J
10. 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
11. 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
12. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 399 J · Wasted: 21 J

12 questions · Seed 48 · 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 360 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (270 ÷ 360) × 100% = 75%.
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 400) × 100% = 40%.
3. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (42 ÷ 120) × 100% = 35%.
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 500 J of total energy and transfers 475 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (475 ÷ 500) × 100% = 95%.
6. A machine is supplied with 200 J of total energy and transfers 170 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (170 ÷ 200) × 100% = 85%.
7. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 180) × 100% = 80%.
8. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (119 ÷ 340) × 100% = 35%.
9. A machine is supplied with 420 J of total energy and transfers 315 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (315 ÷ 420) × 100% = 75%.
10. 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%.
11. 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%.
12. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (399 ÷ 420) × 100% = 95%.

12 questions · Seed 48 · 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 360 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
In: 360 J → Useful: 270 J · Wasted: 90 J
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 160 J · Wasted: 240 J
3. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
In: 120 J → Useful: 42 J · Wasted: 78 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 500 J of total energy and transfers 475 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 475 J · Wasted: 25 J
6. A machine is supplied with 200 J of total energy and transfers 170 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 170 J · Wasted: 30 J
7. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 180 J → Useful: 144 J · Wasted: 36 J
8. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 119 J · Wasted: 221 J
9. A machine is supplied with 420 J of total energy and transfers 315 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 315 J · Wasted: 105 J
10. 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
11. 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
12. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
In: 420 J → Useful: 399 J · Wasted: 21 J

12 questions · Seed 48 · 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 360 J of total energy and transfers 270 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (270 ÷ 360) × 100% = 75%.
2. A machine is supplied with 400 J of total energy and transfers 160 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (160 ÷ 400) × 100% = 40%.
3. A machine is supplied with 120 J of total energy and transfers 42 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (42 ÷ 120) × 100% = 35%.
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 500 J of total energy and transfers 475 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (475 ÷ 500) × 100% = 95%.
6. A machine is supplied with 200 J of total energy and transfers 170 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (170 ÷ 200) × 100% = 85%.
7. A machine is supplied with 180 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
80%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 180) × 100% = 80%.
8. A machine is supplied with 340 J of total energy and transfers 119 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (119 ÷ 340) × 100% = 35%.
9. A machine is supplied with 420 J of total energy and transfers 315 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (315 ÷ 420) × 100% = 75%.
10. 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%.
11. 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%.
12. A machine is supplied with 420 J of total energy and transfers 399 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (399 ÷ 420) × 100% = 95%.

12 questions · Seed 48 · Age guidance, not curriculum certification