V = p1v1 + p2v2/P = 261/2 × 6 + 18 × 41/2/30 = 150 + 81/30 = 8 cu. ft. Ans.
44. Mixture of Two Quantities of Air Having: Unequal Pressures, Volumes, and Temperatures.
If a body of air having a temperature , a pressure , and a volume is mixed with another volume of air having a
temperature , a pressure , and a volume to form a volume having a pressure and a temperature , either the
new temperature , the new volume , or the new pressure
may be found, if the other two quantities are known, by the
following formula, in which , , and are the absolute
temperatures corresponding to , , and :
(1)
It follows from this formula that
(2)
(3)
and(4)
Example 1. — Five cubic feet of air having a pressure of 30 pounds per square inch and a temperature of 80° F. is to be compressed,
together with 11 cubic feet of air having a pressure of 21 pounds per square inch and a temperature of 45° F., in a vessel whose cubical
contents is 8 cubic feet; the new pressure is required to be 45 pounds per square inch. What is the temperature of the mixture?
Solution. — Substituting the given values in formula 4,
° ,nearly
Then,° F. Ans.
Example 2. — Fourteen cubic feet of air at 80 pounds pressure, and
at a temperature of 100° F., is compressed with 26 cubic feet of air at 60 pounds pressure and 60° F. into a volume of 20 cubic feet; what is the resultant pressure, if the final temperature is 140° F.?