00:01
All right, so let's say we have a horizontal pipe where the diameter in one section is 3 .068 inches, and the velocity is 1 .676 meters per second, and the pressure is 68 .9 ,000 pascals.
00:21
And then it narrows to a diameter of 2 .067 inches.
00:29
And we want to know what is the new pressure at that side.
00:34
So the change in pressures is basically going to, since it's a horizontal pipe, it's going to be one -half row v -prime squared minus v -squared, because it only comes from the difference in the flow rates.
00:47
And v -prime is going to be d over d -prime squared times v.
00:53
So we can write the change in pressures in total is one -half row times v squared, times d over d prime square sorry not squared fourth minus one so if we plug in the numbers we have 3 .068 divided by 2 .067 to the fourth minus one times 1 .676 squared divided by 2 .676 squared by 2 times 998 the difference is going to be 5 ,401 .4 pascals and so the pressure at 0 .2 is going to be that much smaller than the pressure on the other side.
01:34
So it'll be about 62 .6 ,000 pascals for rounding.
01:40
And then part b asks, if the pipe is vertical and the flows upwards, calculate the new pressure...