일반물리학 2 — Circuits: Problem 36

36 A standard flashlight battery can deliver about 2.0 W · h of energy before it runs down. (a) If a battery costs US$0.85, what is the cost of operating a 100 W lamp for 8.0 h using batteries? (b) What is the cost if energy is provided at the rate of US$0.06 per kilowatt-hour?