# Velocity of a fluid within a pipe

1. Jun 12, 2013

### tooperoo

1. The problem statement, all variables and given/known data

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.

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

3. The attempt at a solution

I tried using Bernoullis but i keep getting stuck cause i dont know what the pressures at P1 and P2 are.

2. Jun 12, 2013

### Staff: Mentor

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.

3. Jun 12, 2013

### tooperoo

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

Thanks bud!

4. Jun 12, 2013

### Staff: Mentor

What are p1 and p2?

5. Jun 12, 2013

### tooperoo

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

6. Jun 13, 2013

### Staff: Mentor

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