Fluid Mechanics

Question 1

Properties of a solid

Answer 1

definite volume and shape

Question 2

properties of a liquid

Answer 2

has a definite volume but not shape

Question 3

properties of a gas

Answer 3

has neither definite volume nor shape

Question 4

What is a fluid

Answer 4

a collection of molecules held together by weak cohesive forces as well as by forces exerted by the walls of the container

Question 5

which types of matter are fluid

Answer 5

liquids and gases only

Question 6

which force mainly acts on fluids

Answer 6

pressure

Question 7

pressure formula

Answer 7

pressure=force/area

Question 8

in which direction is the force exerted by a static fluid on an object

Answer 8

perpendicular to the object

Question 9

pressure is a scalar or vector

Answer 9

scalar

Question 10

denisity formula

Answer 10

density=mass/volume

Question 11

what does density vary with

Answer 11

temperature

Question 12

what does pressure vary with for fluids

Answer 12

depth

Question 13

if a fluid is at rest in a container, what must be the case

Answer 13

the fluid is in static equilibrium

Question 14

pressure at any given depth formula

Answer 14

P(at depth)=P(at liquids surface)+(ro)(g)(h)

Question 15

what is static pressure on a fluid referred to as?

Answer 15

hydrostatic pressure

Question 16

pascal’s law

Answer 16

p1=p1, therefore F1/A1=F2/A2

Question 17

what is the buoyant force

Answer 17

the buoyant force is the upward force exerted by a fluid on any given submerged object

Question 18

what must be the case if the object is in equilibrium

Answer 18

there must be an equally strong upward force acting on the fluid to balance the gravitational pull

Question 19

Archimedes’ principle qualitatively

Answer 19

when an object is submerged in a fluid, it displaces a volume of fluid equal to its volume

Question 20

Archimedes’ principle in equation form

Answer 20

Fb=roVg. where ro is the denisty of the fluid, V is the volume of fluid displaced.

Question 21

If the density of the object is greater than the density of the fluid

Answer 21

the object sinks

Question 22

If the density of the object is less than the denisty of the fluid

Answer 22

the object accelerates upward

Question 23

Static equilibrium for a floating ca

Answer 23

the upward buoyant force is the balanced by the downward force of gravity.
Also, the volume of fluid displaced is equal to the volume of the object submerged in the fluid

Question 24

Floating object principle in equation form

Answer 24

V(fluid)/V(object)=ro(object)/ro(fluid)

Question 25

The fraction of the volume of the object that is below the surface of the fluid is equal to what

Answer 25

The ratio of the density of the object compared to that of the fluid

Question 26

Why does melting ice not change the volume of the water it was floating on

Answer 26

Because according to archimedes, the volume of fluid displaced is equal to the mass of the object placed in it. When ice melts, it does not change mass therefore the volume displaced is equal to what it was before the ice melted, i.e. it does not change.

Question 27

types of flow of fluids

Answer 27

laminar flow and turbulent flow

Question 28

what is laminar flow

Answer 28

a steady kind of flow is where each particle of fluid follows a straight path called the streamline. The paths of the different particles never cross and every particle of the fluid flows at the same velocity

Question 29

what is turbulent flow

Answer 29

an irregular flow caused by whirlpool regions. it occurs when the particle flow above critical speed

Question 30

viscocity

Answer 30

the degree of internal friction between the two adjancent layers of a fluid

Question 31

Viscosity does not equal density

Answer 31

water and honey have almost the same density yet honey is much much more viscous

Question 32

Ideal fluid flow conditions

Answer 32

1. the fluid is non viscous (no internal friction)
2. the flow is steady (constant velocity)
3. the fluid is incompressible (constant density)
4. flow is irrotational (no angular momentum)

Question 33

what is the direction of the velocity of a particle

Answer 33

tangent to the streamline

Question 34

equation of continuity

Answer 34

V1A1=V2A2

Question 35

flow rate equation

Answer 35

Q=vA where v is velocity and A is the cross sectional area of the opening through which the fluid flows through

Question 36

Bernoulli’s equation

Answer 36

p1+ 1/2(rovi^2)+(roghi)=p2+1/2(rovf^2)+(rogh2)

Question 37

what has to be the case for an object to be neutrally buoyant

Answer 37

Fb(buoyant force)=mg, density of object=density of fluid