Fluids

Question 1

What happens in a liquid?

Answer 1

Molecules flow to the bottom

Question 2

What are some typical density values?

Answer 2

fresh water (4 degrees) = 1000
seawater = 1025
sand = 2600
air = 1.2
helium = 0.18
lead = 11,300

Question 3

What is the hydrostatic equation?

Answer 3

P = density x g x h

works out the mass of fluids

Question 4

What is the pressure of fluids?

Answer 4

Acts at 90 degrees to all surfaces
constant at a given depth
P = 100,000 Nm^-2 at base of atmosphere

Question 5

Pressure at 11,000m depth (challenger)?

Answer 5

approximately 110,600,000 Nm^-2

Question 6

What is archimedes principle?

Answer 6

different forces - net upwards force
bouyancy force
weight of displaced fluid = density x g x V

Question 7

Fluids in motion?

Answer 7

restricted by internal friction

Question 8

What is laminar flow?

Answer 8

intermolecular forces - smooth

low speed, small scale, high viscosity

Question 9

What is turbulent flow?

Answer 9

Momentum change - eddies

high speed, large scale, low viscosity.

Question 10

What is Reynolds number?

Answer 10

defines laminar forces and turbulent forces

Question 11

What is Stokes Law?

Answer 11

sinking objects - laminar

Fd = 3 pi x dynamic viscosity x Diameter x speed

Question 12

Settling velocity for spherical particles in Laminar conditions.

Answer 12

v = ( (density x p - density x F) D^2 g ) / 18 mu