3.2 tons of coal is used to provide enough heat to bring the temperature of 2.0 x l05 gallons of water up 300 f. the heat value of one ton of coal is 2.5 x107 btu/ton. one gallon of water weighs 8 lbs and btu’s are calculated by multiplying pounds of water by their change in temperature in degrees fahrenheit. what is the efficiency?

Click the item in the left column. use the plus sign to move it up or the minus sign to move it down until it matches the correct entry in the right column. lock your answer in place by clicking the square beside the item. (a checkmark means it is locked.) amazon basin a atacama desert b andes mountains c lake titicaca d peru e patagonia f brazil g chile h suriname

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4