00:03
Okay, so we are doing this problem that asked to find the average value of inhaled air in the lungs in one respiratory cycle using a problem from exercise 4 .5, number 57.
00:23
So in that problem from section 4 .5, the answer for the...
00:36
Volume of air function is 5 over 4 pi times 1 minus cosine of 2 pi 2 pi t over 5.
01:00
Okay, so that was the function for the volume of air in terms of t, which is the number of seconds.
01:13
So in this problem, it asks for the average volume of inhaled air in one respiratory cycle.
01:20
So from number 47, one respiratory cycle is 5 seconds.
01:26
So one respiratory cycles equals 5 seconds.
01:32
Okay, so to find the average volume of air in one cycle, which is 5 second, we will use the average value of function formula for any function f.
01:45
It's 1 over b minus a times the integral of a to b of f of x, dx.
01:51
So we know that it's 5 seconds, so a to b is 0 to 5.
01:58
So our integral is going to be 1 over 5 minus 0 of the volume formula.
02:14
Since the problem asked for the average volume.
02:20
So times one times the volume formula, so v of t d t.
02:31
Okay, so that becomes 1 over 5, 0 to 5 times 5 over 4 pi times 1 minus cosine 2 pi t over 5 d t.
02:51
Okay, so simplifying this integral before we integrate, we have 1 over 4 pi from 0 to 5 of 1 minus cosine 2 pi 2 pi t over 5 d t.
03:34
Okay, so now we can integrate.
03:38
And you can integrate by u substitution...