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.
fundamental unit are independent quantities that do not depend on any other unit while derived unit are quantities that depend on two or more units for it definition
Explain why magnetic damping might not be effective on an object made of several thin conducting layers separated by insulation? can someone please explain this i need it for my final exam
An object made of several thin conducting layers separated by insulation may not be affected by magnetic damping because the eddy current produced in each layer due to induction will be very small and the opposing magnetic flux produced by the eddy currents will be very small
Muhammad
What is thê principle behind movement of thê taps control
İt iş diffucult to have idêal machine because of FRİCTİON definitely reduce thê efficiency
Oluwakayode
It is difficult to have an ideal machine in real life situation because in ideal machines all the input energy should be converted to output energy . But , some part of energy is always lost in overcoming friction and input energy is always greater than output energy . Hence , no machine is ideal.
Muhammad
if the classica theory of specific heat is valid,what would be the thermal energy of one kmol of copper at the debye temperature (for copper is 340k)