Bernoulli's principle Flashcards
What is conserved in a close system
mass , energy , momentum
What is a closed system
A system that does not allow the transfer of mass or energy into or out of the system
What is the energy in moving fluids
potential , kinetic and pressure-volume energy. ( we normalize them by dividing the above by volume)
A flying duck is travelling at 20m/s what is the dynamic pressure at it’s beak
dynamic pressure = 1/2 * p * v^2 because it is flying through air it is p = 1.2 kg/m^3 v = 20
What are the assumptions required in Bernoulli’s theorem
- flow is inviscid ( moves without drag/friction)
- flow is incompressible
- flow is laminar
- flow is constant
Describe static pressure
the pressure acting equally at all points perpendicular to a stationary object
What is Bernoulli’s princple
P + 1/2 pv^2 +pgh = constant
Why do we believe that the long necks of the dinosaurs were actually slanted at a small angle
heart would need to overcome a great potential pressure to raise the blood up to high heights as compared to pumping heart to a lower height would require less pressure
What is the law of continuity
Av= constant
flow rate is a constant
When we have fluid flowing through a pipe, why is the top part wider than the bottom
fluid most likely gained energy as it was falling ( due to acceleration by gravity) because flow rate has to be constant by Bernoulli’s law so the cross sectional area decreases
draw what happens when you have an inviscid flow in a pipe compared to viscid flow
energy lost causes the height from each pipe to decrease. friction with the pipe walls causes pressure drop. flow through the pipe is governed by static pressure
What is the Hagen Poiseulle equation
Q = dP * pi * r^4 / ( L * 8 * u) where u is the viscosity
How is blood flow regulated ( think Hagen Poiseulle )
we change the radius through vasodilation or vasoconstriction ( because a change in radius will cause a greater increase in blood flow than when the pressure increases)
What is the difference between gauge and absolute pressure
gauge pressure does not account for atmospheric pressure, whereas absolute pressure needs to account for any factors contributing to pressure
explain how the praire dogs ventilate their burrows
they have a burrow which is elevated this constricts the air above them causing the velocity to increase, the increase in velocity means that the static pressure at the elevated hole decreases, the flat area has a higher static pressure so air moves from the flat hole to the elevated hole through the burrow
