Energy Efficiency Practice Efficiency is the (often measurable) ability to avoid wasting materials, energy, efforts, money, and time in doing
something or in producing a desired result in a more general sense, it is the ability to do things well,
successfully, and without waste. Efficiency is very often confused with effectiveness. In general, efficiency is a
measurable concept, quantitatively determined by the ratio of useful output to total useful input. Effectiveness
is the simpler concept of being able to achieve a desired result, which can be expressed quantitatively but
does not usually require more complicated mathematics than addition,
Efficiency is often measured as the ratio of useful output to total input, which can be expressed with the
mathematical formula r=(PIC) x 100%, where P is the amount of useful output ("product") produced per the
amount C ("cost") of resources consumed.
Answer each of the following questions. Show your work (with units)!
1. 3.2 tons of coal is used to provide enough heat to bring the temperature of 2.0 x 10 gallons of water up
30°F. The heat value of one ton of coal is 2.5 x10' BTU/on. 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
a. How many BTU's are needed to heat the water?
b. How many BTU's were produced when you burned 3.2 tons of coal?