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September 30, 2014

September 30, 2014

Posted by **Dan** on Tuesday, October 28, 2008 at 9:42pm.

v=2(R-r)r^2

i got the derivative:

v'=4rR-6r

what do i do next??

- Calc -
**Damon**, Tuesday, October 28, 2008 at 10:28pmI do not know the question or why you took what you call the derivative but it is not the derivative.

If

v = 2 R r^2 - 2 r^3

then

dv/dr = 4 R r - 6 r^2

However I do not understand where that equation came from.

In general the speed times the area must be constant if the density does not change much.

Therefore

Vo (pi R^2) = v (pi r^2)

v = Vo (R/r)^2

Where Vo is the speed in the open windpipe.

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