Numberphile: Reynolds Number

The second of three videos I made with Numberphile on Fluid Mechanics. Reynolds Number is used to characterise a fluid flow and can lead to amazing results such as time-travelling fluids and the unsolved mystery of turbulence…

 

You can watch part one on the Navier-Stokes equations here.

Thick and sticky fluids

The fourth puzzle in the new feature from Tom Rocks Maths – check out the question below and send your answers to @tomrocksmaths on TwitterFacebook, Instagram or via the contact form on my website. The answer to the last puzzle can be found here.

Viscosity is a property of a fluid on the molecular scale and is a measure of the strength of the internal friction between fluid particles. What this means in practice is that the thicker and stickier the fluid, the higher its viscosity.

Your task in this week’s puzzle is to order the six fluids below by their viscosity, lowest first. The answer will be posted in 2 weeks along with the next puzzle – good luck!

WARNING: answer below image so scroll slowly to avoid revealing it accidentally.

puzzle4

ANSWER

3. Air 1.81 x 10-5 [Pa s]

2. Water 8.9 x 10-4

1. Blood 3 x 10-3 

6. Honey 2-10 [Pa s]

5. Ketchup 50-100 [Pa s]

4. Peanut butter 250 [Pa s]

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