Fluids

Question 1

Predictions about standing fluids

Answer 1

Forces

Question 2

Predictions about moving fluids

Answer 2

Conservation of energy

Question 3

Fluid

Answer 3

Liquid or gas

Molecular bonds constantly breaking/reforming due to high kinetic energy

Question 4

Density

Answer 4

Heaviness of a fluid

Amount of mass in a specified volume

p = m/v

Units = kg/m^3

Question 5

Liquids/solids are _____

Gases are _____

Answer 5

Liquids/solids = incompressible (constant density)

Gases = compressible

Question 6

Specific gravity (SG)

Answer 6

Density of substance compared to density of water

SG =p(substance)/p(water)

Question 7

SG

Answer 7

Substance is lighter than water

Question 8

SG > 1 means …

Answer 8

Substance is heavier than water

Question 9

Density of water

Answer 9

1000kg/m^3

1 g/cm^3

Question 10

Fluid pressure

Answer 10

Pressure experienced by object due to impulse of molecular collisions

Question 11

P = …

Answer 11

P = F/A

Unit = Pascal (Pa)

Question 12

Fluid at rest

Formula for pressure

Answer 12

Experiences only forces perpendicular to surface

P = pgy
y = depth of fluid

Question 13

1 atm = _____ Pa

Answer 13

1 atm = 101,000 Pa

Question 14

Pascal’s principle

Answer 14

Pressure applied anywhere to enclosed incompressible fluid will be distributed undiminished throughout that fluid

Question 15

Buoyant force

Answer 15

Force exerted upward by standing fluid on any object floating, submerged, or sunken

Farther from surface => object experiences greater force and pressure

Question 16

Buoyant force is maximum when…

Answer 16

Fb is maximum when object is fully subermged

Question 17

Fb = …

Answer 17

Fb = p(fluid) * V (fluid) * g

Fb = m(fluid) * g

Question 18

Archimedes Principle

Answer 18

Upward buoyant force is equal in magnitude to weight of displaced fluid

Question 19

Floating object

Answer 19

Mass of fluid displaced = Mass of object

Upward Fb = Downward Fg

Question 20

Fraction of object submerged

Answer 20

p(object)/p(fluid)

*Object floats on top of fluid => numerator

V(fluid) / V(object)

Question 21

Submerged object

Answer 21

Volume of fluid displaced = Volume of object

Upward Fb = Downward Fg

m(fluid) = m(object)

Question 22

Sunk Object

Answer 22

Volume of fluid displaced = Volume of object

Upward Fb

Question 23

Apparent weight loss of object

Answer 23

Density of fluid / Density of object * 100%

*Fluid is on top of object => numerator

Question 24

Moving fluid has what two types of motion

Answer 24

Random translational motion

Uniform translational motion

Question 25

Random translational motion

Answer 25

Contributes to fluid pressure as in a fluid at rest

Question 26

Uniform translational motion

Answer 26

Shared equally by all molecules in a fluid

Does not increase pressure

Question 27

Properties of ideal fluids

Answer 27

No viscosity
Incompressible
Lack turbulence
Irrotational flow

Question 28

Continuity equation (volume flow rate)

Answer 28

Q = Av

```
Q = constant in ideal fluids
A = cross-sectional area
(Q = volume flow rate)
~~~

Question 29

Bernoulli’s Equation

Answer 29

P1 +1/2 p〖v1〗^2+ pgh1 = P2 +1/2 p〖v1〗^2+ pgh2

Multiply any term by volume to get energy

Question 30

Velocity of fluid from spigot

Answer 30

v = Square root(2gh)

Question 31

Venturi effect

Answer 31

Decreased pressure when fluid flows into constricted region of pipe

Question 32

Real fluid movement equation

Answer 32

∆P = Q*R

R = resistance to flow
Similar to Ohm’s Law

Question 33

Effect of radius on flow rate

Answer 33

Small increase in radius => large increase in flow rate

Question 34

Surface tension

Answer 34

Intensity of intermolecular forces of fluid per unit length

Acts like a spring pushing upwards when water molecules are pushed down

Higher temperature = weaker surface tension

Question 35

Intermolecular forces

Answer 35

Pull inward => minimize surface area => spherical shape

Question 36

Capillary action

Answer 36

Fluid pulled up a thin tube is acted on by two forces:

Cohesive forces
Adhesive forces

Question 37

Cohesive forces

Answer 37

Intermolecular forces responsible for ST

Question 38

Adhesive forces

Answer 38

Forces b/w molecules of tube and fluid

Question 39

Cohesive forces > Adhesive forces

Answer 39

Convex surface as fluid is pulled downward by vertical ST component

Question 40

Cohesive forces

Answer 40

Concave surface as fluid is pulled upward by vertical ST component