3.3 Terminal velocity: exercise 2 (example)

Course subject(s) 3. Drag force


A spherical air bubble (density ρair = 1.2 kg/m3) is slowly rising in a bottle of glue at a constant velocity, vs. The bubble has a diameter of 3 mm and rises 2.5 cm in five seconds (easy to measure!). The density of the glue is ρg= 103 kg/m3. With these parameters, you can determine the viscosity of the glue. 

Start with a sketch of the situation!

This is the same graph that we used in the previous exercise about spheres dropped from the roof of a skyscraper, with which we will now attempt to determine the Reynolds number once we know the drag coefficient.

Creative Commons License
The Basics of transport phenomena by TU Delft OpenCourseWare is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at https://ocw.tudelft.nl/courses/basics-transport-phenomena/.
Back to top