Most cars sold in the south are equipped with air conditioners to keep their passengers cool on hot summer days. The air conditioner transfers heat from the air in the passenger compartment to the air outside the car.
1. Where is the evaporator located in a car's air conditioning system?
2. Where is the condenser located in the car's air conditioning system?
3. Why do you get worse gas mileage when you drive with the air conditioner on?
4. The heat exchanger that transfers heat to the outside air is typically located just behind the front grill of the car. Usually there is a fan that can draw air across the heat exchanger. If there were no fan, the air conditioner would do a better job of cooling the car's passengers when the car was moving at high speed than when it was stopped. Explain why in terms of convection.
5. How does the entropy inside of the passenger compartment change as it cools off?
6. If the air conditioner were able to move a given quantity of heat from the air inside the car to the air outside the car without doing any work, how would the increase in entropy of the hot air outside compare to the decrease in entropy of the cool air inside the car?
Although your car is only a year old it already has some scratches and dings.
7. There is a small dent in the top of your car, maybe from where a walnut hit it after falling out of that big tree you were parked under last week. You heard from a friend that there is a simple way to remove the dent. You should park your car in the sun on a hot summer day and let the metal near the dent get nice and hot. Then, you friend tells you, if you place an ice cube in the dent it will pop out. Why might this work?
8. One morning you wake up and there is a thick layer of frost on your car. Rather than scrape the frost off of your windshield you decide to pour a bucket of hot water on it to melt the frost. If your windshield has a small crack in it this may cause the crack to run (become longer). Why?