Ch. 4: Fluids

Question 1

do fluids exert perpendicular or parallel forces

Answer 1

perpendicular

Question 2

equation for density

Answer 2

p = m/V

rho = mass / volume

Question 3

what is the unit of density

Answer 3

kg / m^3

OR g/mL OR g/cm^3

Question 4

what is the density of water

Answer 4

1 g/cm^3

Question 5

equation for weight of a fluid

Answer 5

Fg = pVg

weight = density * volume* acceleration d/t gravity

Question 6

equation for pressure

Answer 6

P = F/A

pressure = force / area

Question 7

what is the unit of pressure

Answer 7

pascal = N/m^2

1 pascal = 1 Newton / m^2

Question 8

equation for absolute pressure

Answer 8

P = Po + pgz

absoulte pressure = incident/ambient pressure + densitygravitydepth

Question 9

equation for gauge pressure

Answer 9

Pgauge = P - Patm = (Po + pgz) - Patm

difference between pressure in an enclosed space and atmospheric pressure

Question 10

Pascal’s principle definition

Answer 10

for fluids that are incompressible, applied pressure is transmitted through the fluid and onto the surfaces containing the fluid.

Question 11

Pascal’s principle equation

Answer 11

P = F1/A1 = F2/A2

F2 = F1 (A2/A1)

Question 12

Buoyant force equation

Answer 12

Fbuoy = p fluid * V fluid displaced * g = p fluid * V submerged * g

Question 13

when will an object sink in a fluid?

Answer 13

objects sink when their density is greater than the density of the fluid

Question 14

cohesion

Answer 14

attractive forces between molecules of a fluid

Question 15

Is surface tension due to cohesion of fluid molecules or adhesion of fluid molecules?

Answer 15

cohesion

Question 16

adhesion

Answer 16

attractive forces between molecules of a fluid and the surfaces containing that fluid

Question 17

what causes a convex meniscus?

Answer 17

when cohesion of a fluid is stronger than adhesion

Question 18

viscosity

Answer 18

resistance of a fluid to flow

Question 19

what is an inviscid fluid?

Answer 19

an ideal fluid with no viscosity that is incapable of experiencing viscous drag

Question 20

what is the unit of viscosit

Answer 20

the pascal-second

Pa * s = (N * s) / m^2

Question 21

Definition of laminar flow

Answer 21

flow that is smooth, orderly, and characterized by LAYERS of fluid running parallel to each other

Question 22

Poiseuille’s law/equation for flow rate

Answer 22

Q = (pi * r^4 * delta P) / 8 * eta * L

flow rate (volume flowing over time) = 
[pi * tube radius^4 * pressure gradient] / [8 * viscosity * length of the pipe]

Question 23

Definition of turbulent flow

Answer 23

flow that is rough and disorderly, and characterized by eddies

Question 24

definition of critical speed

Answer 24

speed at which an unobstructed flowing fluid begins to become turbulent

Question 25

critical speed equation

Answer 25

Vc = [Nr * eta] / [rho * D]

critical speed = (Reynolds number * viscosity) / (density 8 tube diameter)

Question 26

continuity equation/simplified flow rate equation

Answer 26

Q = V1A1 = V2A2

Question 27

Bernoulli’s equation

Answer 27

P1 + 0.5 rhov1^2 + rhogh1 = P1 + 0.5rhov2^2 + rhogh2

static pressure + dynamic pressure is conserved/constant for a system

Question 28

Venturi effect

Answer 28

direct relationship between cross-sectional area and pressure