MODULE 3 SET B Flashcards
study of fluids in motion
FLUID MECHANICS
a subdiscipline of fluid mechanics that describes the flow of fluids
FLUID DYNAMICS
SUBDISCIPLINES OF FLUID DYNAMICS
AERODYNAMICS
HYDRODYNAMICS
path of every particle that passes a particular point moves along exactly the same smooth path followed by previous paticles passing point
STREAMLINE OR LAMINAR
TRUE OR FALSE
The streamline at any point coincides with the direction of the velocity of the fluid at that point
TRUE
it tends to slow the flow of fluid
FRICTION
The fluid closest to the vessel walls moves the —————–
slowest
The fluid in the center of the vessel moves the ——–
fastest
a type of flow where the velocity of the fluid changes layer by layer, or according to the distance from the vessel walls, is called ———–
LAMINAR FLOW
A fluid flow in which the velocity at a given point varies erratically in magnitude and direction
TURBULENT FLOW
thanks, Via
Irregular motions of the fluid, called ———-, are characteritic in turbulent flow.
EDDY CURRENTS
Regions of fluid move in irregular, colliding paths, resulting in mixing and swirling.
TURBULENT FLOW
The volume of fluid passing by a given location through an area during a period of time is called
Q, volume flow rate
FORMULA FOR VOLUME FLOW RATE
Q = Av
A = cross-sectiobal area
v= velocity
The product of the cross-sectional area of the tube and the fluid speed at that cross-section is a constant.
EQUATION OF CONTINUITY
A constricted area = ——- speed
high speed
larger diameter = ——– speed
low speed
TRUE OR FALSE
The volume of the fluid that enters one end of the tube in a given time interval equals the volume of the fluid leaving the tube in the same interval.
TRUE
EQUATION CONTINUITY FORMULA
A1V1=A2V2;
Q1=Q2
SAMPLE PROBLEM
The blood flow speed is 40cm/s in an aorta with a cross-sectional area of 2.0 cm2. Assume that the aorta branches to form a large number of capillaries with a combined cross-sectional area of 3.0 x 10^3 cm2. What is the flow speed in the capillaries?
Vc = 0.027 cm/s
GIVEN: A_a = 2cm^2
v_a= 40cm/s
A_c = 3.0 x 10^3 cm2
He is a Swiss physicist who derived an expression that relates the pressure of a fluid to its speed and elevation in 1738.
DANIEL BERNOULLI
For an incompressible, frictionless fluid, the combination of pressure and the sum of kinetic and potential energy densities is constant not only over time, but also along a streamline.
BERNOULLI’S PRINCIPLE
Mathematically, the Bernoulli’s equation is expressed as
p + pgh + (1/2)pv^2
P = PE due to pressure
pgh = PE due to gravity
(1/2) pv^2 = KE
TRUE OR FALSE
In BERNOULLI’S Principle, fluid flows at a constant depth or height, h1=h2.
TRUE
APPLIES TO SMALL VOLUME OF FLUIDS
TRUE OR FALSE
AS THE VELOCITY OF A FLUID INCREASES, ITS KINETIC ENERGY ALSO INCREASES.
TRUE
TRUE OR FALSE
Pressure drops as speed increases in a moving fluid.
TRUE
TRUE OR FALSE
A high diameter indicates a high pressure.
TRUE
TRUE OR FALSE
A high pressure indicates a high speed.
FALSE
Pressure is inversely proportinal to velocity
TRUE OR FALSE
A smaller diameter pertains to a smaller pressure, but a high velocity.
TRUE
PRACTICE PROBLEM:
The volumetric flow rate of blood in a person at rest is about 5.0 L per minute. If the aorta (the central artery carrying the blood from the heart) has a diameter of 2.0 cm, what is the kinetic energy of blood flowing through the aorta? pblood = 1060 kg/m^3.
37.30 J/m^3
refers to the internal friction of a fluid
VISCOSITY
The fluid flows through the tube because of ———–.
PRESSURE DIFFERENCE
The rate of flow (volume per unit time) depends on the ——————–.
PRESSURE DIFFERENCE
The greater the pressure differejntial between two points, the ————– the flow rate.
the greater the flow rate
A French scientist who derived the law of resistance in an attempt to understand the flow of blood through the body
J. L. POISEUILLE
It states that the rate of flow should increase if the pressure difference across the tube or the tube radius increases.
POISEUILLE’S LAW FOR RESISTANCE
TRUE OR FALSE
The flow rate decrease as the viscosity of the fluid or the length of the tube increases.
TRUE
TRUE OR FALSE
Q = (P2 - P1)/L
TRUE
Q directly proportional to pressure diffrnce;inversely proportional to L
TRUE OR FALSE
The viscosity of blood increases as the number of red blood cells increases.
TRUE
TRUE OR FALSE
In a case where flow rate is constant, viscous friction reduces the pressure.
TRUE
TRUE OR FALSE
Pressure drop is inversely proportional to the radius to the fourth power.
TRUE
A small change in radius = big change to pressure drop
PRACTICE PROBLEM
The volumetric flow rate of blood in a person at rest is about 5L per minute. The beginning of the aorta (the path closest to the heart) has a diameter of 3cm, but the end of the aorta in the lower abdomen has a diameter of only 1.75 cm.
a. what is the flow rate of blood at the beginning of the aorta in m/s?
b. what is the flow rate of blood at the end of the aorta in the lower abdomen in m/s?
c. how much faster is the blood travelling at the end of the aorta than it is at the beginning?
a. 0.118 m/s
b. 0.346 m/s
c. 0.228 m/s
PRACTICE PROBLEM
Water flows through a tube with a diameter of 2m at a rate of 800 kg/s. What is the velocity of water?
0.25m/s
https://www.varsitytutors.com/ap_physics_2-help/flow-rate
PRACTICE PROBLEM
Suppose that water flows from a pipe with a diameter of 1m into another pipe of diameter 0.5m. If the speed of water in the first pipe is 5m/s, what is the speed in the second pipe?
20 m/s
https://www.varsitytutors.com/ap_physics_2-help/flow-rate
PRACTICE PROBLEM
A diameter garden hose with a diameter of 3cm sprays water travels through a hose at 1m/s. At the end of the garden hose, the diameter reduces to 2cm. What is the speed of the water coming out at the end?
2.25 m/s
https://www.varsitytutors.com/ap_physics_2-help/flow-rate
PRACTICE PROBLEM
An incompressible fluid flows through a pipe. At location 1 along the pipe, the volume flow rate is 10m^3/s. At location 2 along the pipe, the area halves. What is the volume flow rate at location 2?
10m^3/s
https://www.varsitytutors.com/ap_physics_2-help/flow-rate
PRACTICE PROBLEM
What is the volumetric flow rate of ethanol flowing through a square pipe with sidelength 4m? The velocity of the ethanol is 7m/s.
112 m^3/s
https://www.varsitytutors.com/ap_physics_2-help/flow-rate
PRACTICE PROBLEM
A pipe narrows from a 30m diameter to a 15m diameter. What is the velocity of the fluid when it exits the pipe (at the 15m end) if it entered the pipe at 15m/s?
60 m/s
https://www.varsitytutors.com/ap_physics_2-help/flow-rate
