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Efficiency and waste heat — Homework
Use efficiency = (useful energy out / total energy in) x 100 for every problem.
- 1.A machine receives 80 J and outputs 60 J of useful work. Find its efficiency.
- 2.A device is 50% efficient and receives 40 J. Find its useful output.
- 3.A motor is 90% efficient and produces 45 J of useful output. Find its total input.
- 4.A car engine is only about 25% efficient turning gasoline's energy into motion. What happens to the other 75%?
- 5.Why does a laptop charger feel warm while working?
🌲 Homeschool of the FutureEighth Grade · Science · week 16 homework