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.

New variation Try interactive challenge Browse templates

Age band:Ages 10-12 Ages 13-15

Choose “Save as PDF” to keep a copy. Use your browser’s paper setting for A4 or Letter.

Worksheet StudioPractice pack · Ages 10-12

Percentage energy efficiency

Take your time. Show your thinking.

1. 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
2. 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
3. A machine is supplied with 500 J of total energy and transfers 150 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 150 J · Wasted: 350 J
4. A machine is supplied with 80 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 36 J · Wasted: 44 J
5. A machine is supplied with 480 J of total energy and transfers 432 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 432 J · Wasted: 48 J
6. A machine is supplied with 460 J of total energy and transfers 207 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 207 J · Wasted: 253 J
7. A machine is supplied with 240 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 216 J · Wasted: 24 J
8. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 49 J · Wasted: 91 J
9. A machine is supplied with 160 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 32 J · Wasted: 128 J
10. 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
11. 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
12. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 380 J · Wasted: 20 J

12 questions · Seed 42 · 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 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%.
2. 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%.
3. A machine is supplied with 500 J of total energy and transfers 150 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (150 ÷ 500) × 100% = 30%.
4. A machine is supplied with 80 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 80) × 100% = 45%.
5. A machine is supplied with 480 J of total energy and transfers 432 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (432 ÷ 480) × 100% = 90%.
6. A machine is supplied with 460 J of total energy and transfers 207 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (207 ÷ 460) × 100% = 45%.
7. A machine is supplied with 240 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (216 ÷ 240) × 100% = 90%.
8. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (49 ÷ 140) × 100% = 35%.
9. A machine is supplied with 160 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (32 ÷ 160) × 100% = 20%.
10. 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%.
11. 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%.
12. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (380 ÷ 400) × 100% = 95%.

12 questions · Seed 42 · 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 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
2. 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
3. A machine is supplied with 500 J of total energy and transfers 150 J as useful energy output. Calculate its percentage efficiency.
In: 500 J → Useful: 150 J · Wasted: 350 J
4. A machine is supplied with 80 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
In: 80 J → Useful: 36 J · Wasted: 44 J
5. A machine is supplied with 480 J of total energy and transfers 432 J as useful energy output. Calculate its percentage efficiency.
In: 480 J → Useful: 432 J · Wasted: 48 J
6. A machine is supplied with 460 J of total energy and transfers 207 J as useful energy output. Calculate its percentage efficiency.
In: 460 J → Useful: 207 J · Wasted: 253 J
7. A machine is supplied with 240 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
In: 240 J → Useful: 216 J · Wasted: 24 J
8. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
In: 140 J → Useful: 49 J · Wasted: 91 J
9. A machine is supplied with 160 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
In: 160 J → Useful: 32 J · Wasted: 128 J
10. 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
11. 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
12. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
In: 400 J → Useful: 380 J · Wasted: 20 J

12 questions · Seed 42 · 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 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%.
2. 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%.
3. A machine is supplied with 500 J of total energy and transfers 150 J as useful energy output. Calculate its percentage efficiency.
30%
Efficiency = (useful energy output ÷ total energy input) × 100% = (150 ÷ 500) × 100% = 30%.
4. A machine is supplied with 80 J of total energy and transfers 36 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (36 ÷ 80) × 100% = 45%.
5. A machine is supplied with 480 J of total energy and transfers 432 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (432 ÷ 480) × 100% = 90%.
6. A machine is supplied with 460 J of total energy and transfers 207 J as useful energy output. Calculate its percentage efficiency.
45%
Efficiency = (useful energy output ÷ total energy input) × 100% = (207 ÷ 460) × 100% = 45%.
7. A machine is supplied with 240 J of total energy and transfers 216 J as useful energy output. Calculate its percentage efficiency.
90%
Efficiency = (useful energy output ÷ total energy input) × 100% = (216 ÷ 240) × 100% = 90%.
8. A machine is supplied with 140 J of total energy and transfers 49 J as useful energy output. Calculate its percentage efficiency.
35%
Efficiency = (useful energy output ÷ total energy input) × 100% = (49 ÷ 140) × 100% = 35%.
9. A machine is supplied with 160 J of total energy and transfers 32 J as useful energy output. Calculate its percentage efficiency.
20%
Efficiency = (useful energy output ÷ total energy input) × 100% = (32 ÷ 160) × 100% = 20%.
10. 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%.
11. 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%.
12. A machine is supplied with 400 J of total energy and transfers 380 J as useful energy output. Calculate its percentage efficiency.
95%
Efficiency = (useful energy output ÷ total energy input) × 100% = (380 ÷ 400) × 100% = 95%.

12 questions · Seed 42 · Age guidance, not curriculum certification