A standard flashlight battery can deliver about 4.9 W·h of energy before it runs down. (a) If a battery costs 80 cents, what is the cost in dollars of operating a 100 W lamp for 9.0 h using batteries? (b) What is the cost in dollars if power is provided at the rate of 6.0 cents per kilowatt-hour?

Problem 6:  Suppose the cost of an incandescent bulb is 23 cents and that electricity costs 12 cents/kWh. Compact fluorescent lightbulbs (CFL), while they are more expensive, use 1/10 of the power for the same amount of illumination. What would be the maximum cost (in dollars) of a CFL such that the total cost (investment plus operating) would be the same for both CFL and incandescent 60 W bulbs? Assume both lightbulbs run for 1000 h.

A battery-operated car utilizes a 12.0 V system. Find the charge the batteries must be able to move in order to accelerate the 750 kg car from rest to 25.0 m/s, make it climb a 2.00×102 m high hill, and then cause it to travel at a constant 25.0 m/s by exerting a 5.00×102 N force for an hour.

In the figure ℰ1 = 3.22 V, ℰ2 = 0.927 V, R1 = 3.89 Ω, R2 = 2.23 Ω, R3 = 3.65 Ω, and both batteries are ideal. What is the rate at which energy is dissipated in (a) R1, (b) R2, and (c) R3? What is the power of (d) battery 1 and (e) battery 2?