# Equation of continuity with aorta and the forces exerted on an underwater vehicle

1. Feb 3, 2008

### PhysicsHelp08

I'm having a lot of trouble with fluids I need some help on these two questions :/

the mariana trench is located in the floor of the Pacific Ocean at a depth of about 11 000 m below the surface of the water. The density of seawater is 1025 kg/m^3.
if an underwater vehicle were to explore such a depth, what force would the water exert on the vehicles observation window (radius=.10m)?
For comparison, determine the weight of a jetliner whose mass is 1.2x10^5 kg

The aorta carries blood away from the heart at a speed of 40 cm/s and has a radius of 1.1cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to various organs. In a capillary, the blood speed is about .07 cm/s and the radius is about 6x10^-4cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body

any help please? thanks a lot!

2. Feb 3, 2008

### MuffinMan616

Ok... I am new to this forum but I noticed your post and thought I'd lent a hand. I am enrolled in Advanced Placement Physics at my high school and we already went over fluids so I think i can help.

For your first question:

P = p*g*h
P = F/A
A = pi*r^2
--so--
F=P*A
--and--
F=p*g*h*pi*r^2

and the other part:

F = ma
--so--
Fg = m*g

For the second question:

It is flow rate...

AV(before) = AV(after)
A = pi*r^2
--so--
pi*r^2*V = pi*r^2*V

since there are multiple capilaries...

r(of aorta)^2*V(of a.)
------------------------ (divided by) = Number of capilaries
r(of capilaries)^2*V(of c.)

Hope this helped

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