# physics

posted by .

What power - in Watt-hours - is needed at home on your standard 115 V circuit to run: (a) a
10 A air conditioner for one hour to completely cool off your room, or (b) a 3 A electric fan to
keep a constant flow of air over you for five hours? (c) Which is more efficient for you to use?
and (d) Why would your choice be more efficient?

• physics -

(a) A 115 V that draws 10 A consumes up to 1.150 kilowatts. In one hour, that is 1.15 kwh. This assumes a "power factor" of 1. The meaning of power factor in AC circuits should have been explained to you.
(b) A 115 V, 3A fan consumes 1.725 kwh in five hours.

Multiply both by 1000 for watt-hours.

(c) They should define efficiency. A fan will not cool you if the humidity is 100%. The A/C will be much more comfortable. If the A/C is only on for one hour, the room will heat up again, unless the A/C is cycling on and off during the five hours.

There are many things wrong with this question

## Similar Questions

1. ### AP chemistry

A typical electric air conditioner rated at 1.00 * 10^4 Btu/h (1 Btu = amount of energy required to raise the temperature of 1 lb of water by 1F). How much water must be evaporated each hour to dissipate as much heat as a typical electric …
2. ### math

Consumers pay for electricity by the kilowatt-hour (the amount of electricity used by a 1,000-watt appliance in one hour). If electricity costs 10cents per kilowatt-hour, what is the cost of running a 100-watt lamp for 1. 1 hour?
3. ### science

An air condition lowers the temperature of the surrounding air.Water condensed from air is mostly likely to run out of the bottom water hose of an automobile air conditioner when the air entering the air conditioner is
4. ### Physics

Suppose your power company charges \$1.00 per kWh as its power rate. (a) What is the power in kW for an air conditioner that pulls 5 A on your standard 115 V household circuit?
5. ### physics

Consider a room air conditioner using a Carnot cycle at maximum theoretical efficiency and operating between the temperatures of 19.7°C (indoors) and 28.7°C (outdoors). For each 1.00 J of heat flowing out of the room into the air …
6. ### physics

a window air conditioner is estimated to have a cost of operation of \$50 per 30 days. this is based on the assumption that the air conditioner will run half of the time and that electricity costs \$.090 per kWh. determine how much current …
7. ### physics

1. A typical household circuit is capable of carrying 15.0 Amps of current at 120 V before the circuit breaker will trip. How many 1500-W hair dryers can run off one such circuit?
8. ### physics

A window air conditioner consumes 900 W of electric power and has COP = 2.9.If it runs continuously for 24 h , how much heat gets removed from the house?
9. ### algebra

The cost of operating an appliance varies jointly as the number of watts, hours of operation, and the cost per kilowatt-hours. It costs \$0.45 to operate a 3000-watt air conditioner for 2 hours at a cost of \$0.075 per kilowatt-hour. …

More Similar Questions