Introduction to Laboratories
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For 1, 3, and 5, there are no substantial submissions - you have to analyze the data, but you don’t have to produce any graphs.
FM2 labs support the lectures, but they also build your professional skills.
You have to show: - Beautiful and effective graphs - Dealing with uncertainty - Drawing good conclusions
1 Drag Laboratory
Reminder: the drag force equation is
F_D = \frac{1}{2}C_D \rho p A u^2
The point of the lab is to measure the relationship between the drag coefficient and Reynolds number for a portion of the graph.
Re = \frac{\rho_f u D}{\mu}
Large and fast objects, travelling in low viscosity fluid, have greater Reynolds numbers than the obverse.
We will be dropping small aluminum / plastic spheres down columns of water and oil, recreating a small range of Reynolds numbers.
We know the density and viscosity of the fluid (\rho_f, \mu), we know the diameter of the sphere, and we will time the descent of the sphere to find its velocity.
To find the drag force on the sphere, we use this free body diagram.
F_D = F_W - F_B
F_D is the drag force, the unknown we wish to solve. F_W is the mass of the sphere times g, which can be directly measured (or calculated using the density of the sphere), and F_B is the force of buoyancy, which equals \rho \dot g \dot V.
2 Excel sheet for the lab
The excel sheet is prepared as follows:
- Set up a new excel workbook and copy the properties of the