Velocity of a fluid within a pipe

[tooperoo]

Homework Statement

A scientist attempts to model the flow of blood through an artery using a hollow pipe of diameter 1.8cm. A fluid density 1060kg/m^3 is used to simulate blood in the pipe. Viscous effects can be considered to be negligible.

TO study a blockage in an artery, the scientist holds the pipe horizontally and places a constriction in the pipe reducing the diameter to 1.1 cm. What is the speed of the fluid as it passes through the narrowest point of the blockage? Assume that the speed in the un-constricted region is 0.75m/s.

Homework Equations

Bernoulli's
P1 + 1/2pV1^2 +pgh = P2 + 1/2pV2^2 +pgh

The Attempt at a Solution

I tried using Bernoullis but i keep getting stuck cause i don't know what the pressures at P1 and P2 are.

 

[mfb]

You don't need any pressures, just consider that mass does not vanish in the pipe: mass flow has to be the same everywhere, and you can assume that blood cannot be compressed.

 

[tooperoo]

Ohhh, so I should use the formula p1*v1*A1 = p2*v2*A2?Thanks bud!

 

[mfb]

What are p1 and p2?

 

[tooperoo]

My apologies, p1 and p2 are the density. I think they're called rho?

 

[mfb]

Ah, okay.
Well, blood cannot be compressed (in relevant amounts).