Problem 1: Viscometer data of honey [12]

Viscometers are instruments designed to measure the viscosity of a fluid. Imagine a viscometer

that applies a shear (tangential force) to a fluid, and measures the force required to apply this

shear (the shear stress). Example data from a viscometer is shown below, where the shear stress

as a function of the velocity gradient (here, the rate of shear strain) is tabulated. The data below

is for different types of honey adapted from:

Santos, Francisco Klebson & Filho, Antonio & Leite, R.H.L. & Aroucha, Edna & Santos,

Andarair & Oliveira, Thiago. (2014). Rheological and some physicochemical characteristics of

selected floral honeys from plants of caatinga. Anais da Academia Brasileira de Ciências. 86.

10.1590/0001-3765201420130064.

Shear stress as a function of strain rate for different types of honey

shear rate (1/s) shear stress (Pa)

croton

camprestris

0

10

20

30

40

CHE330, Fall 2023

50

60

70

80

90

0

18

40

52

60

91

105

130

145

170

cobretum

leprosum

0

48

105

HW#2

149

199

255

310

351

385

444

mimosa

tenufiora

0

88

178

249

344

420

a. [5] Plot the data on a graph of shear stress as a function of shear rate. Since you have

individual data points, plot individual points. You may use any type of software, but Excel is

520

597

669

771

recommended. Make sure your plot shows data points, legend, and has labelled axes

including units.

b. [2] What type of fluid is honey (Newtonian, shear thinning, shear thickening)? Explain

your answer using your graph.

c. [5] If a fluid is Newtonian, you can fit a linear trendline through the data from part a,

forcing the intercept through the origin. Show the trendline and the equation of the trendline

on the plot (note that the intercept of the trendline must be zero- you can force it through zero

in the trendline setup in Excel). Determine the viscosity of each type of honey in cP.