Laminar flow is characterized by smooth flow of the fluid in layers that do not mix.
Turbulence is characterized by eddies and swirls that mix layers of fluid together.
Fluid viscosity
$\eta $ is due to friction within a fluid. Representative values are given in
[link] . Viscosity has units of
$({\text{N/m}}^{2})\text{s}$ or
$\text{Pa}\cdot \text{s}$ .
Flow is proportional to pressure difference and inversely proportional to resistance:
$Q=\frac{{P}_{2}-{P}_{1}}{R}.$
For laminar flow in a tube, Poiseuille’s law for resistance states that
$R=\frac{8\eta l}{{\mathrm{\pi r}}^{4}}.$
Poiseuille’s law for flow in a tube is
$Q=\frac{({P}_{2}-{P}_{1})\pi {r}^{4}}{8\eta l}.$
The pressure drop caused by flow and resistance is given by
${P}_{2}-{P}_{1}=RQ.$
Conceptual questions
Explain why the viscosity of a liquid decreases with temperature—that is, how might increased temperature reduce the effects of cohesive forces in a liquid? Also explain why the viscosity of a gas increases with temperature—that is, how does increased gas temperature create more collisions between atoms and molecules?
When paddling a canoe upstream, it is wisest to travel as near to the shore as possible. When canoeing downstream, it may be best to stay near the middle. Explain why.
(a) Calculate the retarding force due to the viscosity of the air layer between a cart and a level air track given the following information—air temperature is
$\text{20\xba C}$ , the cart is moving at 0.400 m/s, its surface area is
$2\text{.}\text{50}\times {\text{10}}^{\mathrm{-2}}\phantom{\rule{0.25em}{0ex}}{\text{m}}^{2}$ , and the thickness of the air layer is
$6.00\times {\text{10}}^{-5}\phantom{\rule{0.25em}{0ex}}\text{m}$ . (b) What is the ratio of this force to the weight of the 0.300-kg cart?
What force is needed to pull one microscope slide over another at a speed of 1.00 cm/s, if there is a 0.500-mm-thick layer of
$\text{20\xba C}$ water between them and the contact area is
$8.00\phantom{\rule{0.25em}{0ex}}{\text{cm}}^{2}$ ?
A glucose solution being administered with an IV has a flow rate of
$4\text{.}\text{00}\phantom{\rule{0.25em}{0ex}}{\text{cm}}^{3}\text{/min}$ . What will the new flow rate be if the glucose is replaced by whole blood having the same density but a viscosity 2.50 times that of the glucose? All other factors remain constant.
The pressure drop along a length of artery is 100 Pa, the radius is 10 mm, and the flow is laminar. The average speed of the blood is 15 mm/s. (a) What is the net force on the blood in this section of artery? (b) What is the power expended maintaining the flow?
A small artery has a length of
$1\text{.}1\times {\text{10}}^{-3}\phantom{\rule{0.25em}{0ex}}\text{m}$ and a radius of
$2.5\times {\text{10}}^{-5}\phantom{\rule{0.25em}{0ex}}\text{m}$ . If the pressure drop across the artery is 1.3 kPa, what is the flow rate through the artery? (Assume that the temperature is
$\text{37\xba C}$ .)
Fluid originally flows through a tube at a rate of
$\text{100}\phantom{\rule{0.25em}{0ex}}{\text{cm}}^{3}\text{/s}$ . To illustrate the sensitivity of flow rate to various factors, calculate the new flow rate for the following changes with all other factors remaining the same as in the original conditions. (a) Pressure difference increases by a factor of 1.50. (b) A new fluid with 3.00 times greater viscosity is substituted. (c) The tube is replaced by one having 4.00 times the length. (d) Another tube is used with a radius 0.100 times the original. (e) Yet another tube is substituted with a radius 0.100 times the original and half the length,
and the pressure difference is increased by a factor of 1.50.
Calculate the work done by an 85.0-kg man who pushes a crate 4.00 m up along a ramp that makes an angle of 20.0º20.0º with the horizontal. (See [link] .) He exerts a force of 500 N on the crate parallel to the ramp and moves at a constant speed. Be certain to include the work he does on the crate an
static fiction is friction between two surfaces in contact an none of sliding over on another, while Kinetic friction is friction between sliding surfaces in contact.
MINDERIUM
I don't get it,if it's static then there will be no friction.
author
It means that static friction is that friction that most be overcome before a body can move
kingsley
static friction is a force that keeps an object from moving, and it's the opposite of kinetic friction.
author
It is a force a body must overcome in order for the body to move.
Eboh
If a particle accelerator explodes what happens
Eboh
why we see the edge effect in case of the field lines of capacitor?
Force equals mass time acceleration. Weight is a force and it can replace force in the equation. The acceleration would be gravity, which is an acceleration. To change from weight to mass divide by gravity (9.8 m/s^2).
the write question should be " How many Topics are in O- Level Physics, or other branches of physics.
effiom
how many topic are in physics
Praise
Praise what level are you
yusuf
If u are doing a levels in your first year you do AS topics therefore you do 5 big topic i.e particles radiation, waves and optics, mechanics,materials, electricity. After that you do A level topics like Specific Harmonic motion circular motion astrophysics depends really
Anya
Yeah basics of physics prin8
yusuf
Heat nd Co for a level
yusuf
yh I need someone to explain something im tryna solve . I'll send the question if u down for it
a ripple tank experiment a vibrating plane is used to generate wrinkles in the water .if the distance between two successive point is 3.5cm and the wave travel a distance of 31.5cm find the frequency of the vibration
Tamdy
hallow
Boniface
please send the answer
Boniface
the range of objects and phenomena studied in physics is