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## Homework Statement

The following image shows the parts A and B of a pipe where the middle part goes under a hill the length of both parts A and B is 30m and the diameter of them each is 2cm where as the middle part has a length of 110m to determine the middle part's diameter one engineer decided to push water in the pipe with a speed of 2.50 m\s in part A he dropped a small coin in the flow and noticed that it took 88.8 seconds for it to start from A and exit from B.

1)calculate the diameter of the middle pipe

## Homework Equations

v=d\s

A1*v1=A2*v2. (Continuity equation)

A=pi*r^2[/B]

## The Attempt at a Solution

Finding the area of a and b:

0.02^2*pi=0.00125m^2

Finding the time it would take to travel through A and B (not including mid pipe)

2.50=30/s

s=12

So for a and b it would take 24 seconds

For mid part it would take 88.8-24=64.8

Mid part speed

110/64.8=1.697m\s

So

0.00125*2.50=1.697*A2

Area=0.001841

0.0018141=pi*r^2

R=0.024m

Answer sheet says that the diameter is 3.60cm

help!