AP Environmental Science s3

Name ______

Do the following problems without using your calculator. Show all of your work in order to get credit, and circle your final answer. Be sure to include units throughout your problems.

1. Estimate the potential reduction in petroleum consumption (in gallons of gasoline per year) that could be achieved in the United States by introducing electric vehicles under the following assumptions:  the mileage rate for the average car is 25 miles per gallon of gasoline  the average car is driven 10,000 miles per year  the US has 150 million cars  10% of US cars could be replaced with electric vehicles  assume the electric cars do not use any gasoline

2. Looking at your electric bill, you see that last month your meter read 4521 kWh. This month your meter reads 5023 kWh. To determine your monthly use, you subtract the meter readings. Assume your bill was $42.67 for the 31-day billing period. (A) What was your rate per kWh (to 3 decimal places)?

(B) Convert your kWh into kJ.

(C) What was the average cost per day?

(D) Assume you were able to cut your lights off more often next month, but everything else remained the same. If you cut down your bill by 36 kWh, how much will your bill be (in dollars) next month? 3. Water resists changes in temperature. In other words, it takes a lot of heat energy to make a small change in the temperature of water. Therefore, water heaters are quite expensive to operate. It takes 1 BTU of heat energy to raise the temperature of 1 pound of water 1 degree F. Assume that the water entering the water heater enters at 40 degrees F and leaves the heater at 120 degrees F. (A) How many BTUs of heat energy would be lost in 1 year if a leaky faucet wastes 4.0 pounds of water / day? (A dripping faucet with only 3 drops per minute, each drop 0.5 ml, will waste 4320 drips a day or about 1 liter)

(B) If each KWh of energy cost the homeowner $0.046, how much money would he/she waste per year? (one kilowatt-hour is equal to 3,413 BTUs)

(C) How many gallons a year are wasted if one gallon of water weighs 8.34 lbs.?

(D) How many gallons of water are wasted per day?

(E) If there are 4 cups in a quart and 4 quarts in a gallon, how many cups of water is this daily?

http://ga.water.usgs.gov/edu/sc4java.html Good site for water waste information