Lesson: Viscosity and Turbulence

In this lesson, we will learn how to use Poiseuille's law for laminar fluid flow and how to model the onset of turbulence with Reynolds numbers.

Video

11:23

Sample Question Videos

  • 08:08
  • 10:44

Worksheet: 23 Questions • 2 Videos

Q1:

Stokes’ law describes sedimentation of particles in liquids and can be used to measure viscosity. Particles in liquids achieve terminal velocity quickly. One can measure the time it takes for a particle to fall a certain distance and then use Stokes’ law to calculate the viscosity of the liquid. Suppose a steel ball bearing (density 7.8×10 kg/m3, diameter 3.0 mm) is dropped in a container of motor oil. It takes 12 s to fall a distance of 0.60 m. Calculate the viscosity of the oil.

Q2:

The pressure difference across the tube increases by a factor of 1.50. What is the flow rate through the tube if no other changes are made?

A fluid with a viscosity 3.00 times greater than that of the original fluid flows through the tube. What is the flow rate through the tube if no other changes are made?

The length of the tube is increased by a factor of 4.00. What is the flow rate through the tube if no other changes are made?

The radius of the tube is reduced by a factor of 10.0. What is the flow rate through the tube if no other changes are made?

The radius of the tube is reduced by a factor of 10.0. The length of the tube is reduced by a factor of 2.00, and the pressure difference across the tube is increased by a factor of 1.50. What is the flow rate through the tube if no other changes are made?

Q3:

A small artery has a length of 1.1×10 m and a radius of 2.5×10 m. If the pressure drop across the artery is 1.3 kPa, what is the flow rate through the artery if the viscosity of the blood is 2.084×10 Pa⋅s?

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