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 320 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 144 J · Wasted: 176 J
2. A machine is supplied with 480 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 240 J · Wasted: 240 J
3. A machine is supplied with 380 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 152 J · Wasted: 228 J
4. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 437 J · Wasted: 23 J
5. A machine is supplied with 340 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 306 J · Wasted: 34 J
6. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 57 J · Wasted: 3 J
7. A machine is supplied with 280 J of total energy and transfers 238 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 238 J · Wasted: 42 J
8. A machine is supplied with 200 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 90 J · Wasted: 110 J
9. A machine is supplied with 380 J of total energy and transfers 285 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 285 J · Wasted: 95 J
10. A machine is supplied with 280 J of total energy and transfers 266 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 266 J · Wasted: 14 J
11. A machine is supplied with 240 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 48 J · Wasted: 192 J
12. A machine is supplied with 40 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 30 J · Wasted: 10 J

12 questions · Seed 104736 · 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 320 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 320) × 100% = 45%.
2. A machine is supplied with 480 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 480) × 100% = 50%.
3. A machine is supplied with 380 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (152 ÷ 380) × 100% = 40%.
4. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (437 ÷ 460) × 100% = 95%.
5. A machine is supplied with 340 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (306 ÷ 340) × 100% = 90%.
6. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 60) × 100% = 95%.
7. A machine is supplied with 280 J of total energy and transfers 238 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (238 ÷ 280) × 100% = 85%.
8. A machine is supplied with 200 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 200) × 100% = 45%.
9. A machine is supplied with 380 J of total energy and transfers 285 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (285 ÷ 380) × 100% = 75%.
10. A machine is supplied with 280 J of total energy and transfers 266 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (266 ÷ 280) × 100% = 95%.
11. A machine is supplied with 240 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 240) × 100% = 20%.
12. A machine is supplied with 40 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 40) × 100% = 75%.

12 questions · Seed 104736 · 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 320 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
In: 320 J → Useful: 144 J · Wasted: 176 J
2. A machine is supplied with 480 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 240 J · Wasted: 240 J
3. A machine is supplied with 380 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 152 J · Wasted: 228 J
4. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 437 J · Wasted: 23 J
5. A machine is supplied with 340 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
In: 340 J → Useful: 306 J · Wasted: 34 J
6. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
In: 60 J → Useful: 57 J · Wasted: 3 J
7. A machine is supplied with 280 J of total energy and transfers 238 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 238 J · Wasted: 42 J
8. A machine is supplied with 200 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
In: 200 J → Useful: 90 J · Wasted: 110 J
9. A machine is supplied with 380 J of total energy and transfers 285 J as useful energy output. Calculate its percentage efficiency.
In: 380 J → Useful: 285 J · Wasted: 95 J
10. A machine is supplied with 280 J of total energy and transfers 266 J as useful energy output. Calculate its percentage efficiency.
In: 280 J → Useful: 266 J · Wasted: 14 J
11. A machine is supplied with 240 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 48 J · Wasted: 192 J
12. A machine is supplied with 40 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
In: 40 J → Useful: 30 J · Wasted: 10 J

12 questions · Seed 104736 · 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 320 J of total energy and transfers 144 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (144 ÷ 320) × 100% = 45%.
2. A machine is supplied with 480 J of total energy and transfers 240 J as useful energy output. Calculate its percentage efficiency.
50%
Efficiency = (useful energy output ÷ total energy input) × 100% = (240 ÷ 480) × 100% = 50%.
3. A machine is supplied with 380 J of total energy and transfers 152 J as useful energy output. Calculate its percentage efficiency.
40%
Efficiency = (useful energy output ÷ total energy input) × 100% = (152 ÷ 380) × 100% = 40%.
4. A machine is supplied with 460 J of total energy and transfers 437 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (437 ÷ 460) × 100% = 95%.
5. A machine is supplied with 340 J of total energy and transfers 306 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (306 ÷ 340) × 100% = 90%.
6. A machine is supplied with 60 J of total energy and transfers 57 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (57 ÷ 60) × 100% = 95%.
7. A machine is supplied with 280 J of total energy and transfers 238 J as useful energy output. Calculate its percentage efficiency.
85%
Efficiency = (useful energy output ÷ total energy input) × 100% = (238 ÷ 280) × 100% = 85%.
8. A machine is supplied with 200 J of total energy and transfers 90 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (90 ÷ 200) × 100% = 45%.
9. A machine is supplied with 380 J of total energy and transfers 285 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (285 ÷ 380) × 100% = 75%.
10. A machine is supplied with 280 J of total energy and transfers 266 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (266 ÷ 280) × 100% = 95%.
11. A machine is supplied with 240 J of total energy and transfers 48 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (48 ÷ 240) × 100% = 20%.
12. A machine is supplied with 40 J of total energy and transfers 30 J as useful energy output. Calculate its percentage efficiency.
75%
Efficiency = (useful energy output ÷ total energy input) × 100% = (30 ÷ 40) × 100% = 75%.

12 questions · Seed 104736 · Age guidance, not curriculum certification