One type of rotating cylinder viscometer, called a Stormer viscometer, uses a falling we...

One type of rotating cylinder viscometer, called a Stormer viscometer, uses a falling weight, w, to cause the cylinder to rotate with an angular velocity, ω, as illustrated in Fig. P1.54. For this device the viscosity, μ, of the liquid is related to w and ω through the equation where K is a constant that depends only on the geometry (including the liquid depth) of the viscometer. The value of K is usually determined by using acalibration liquid (a liquid of known viscosity).

(a) Some data for a particular Stormer viscometer, obtained using glycerin at 20 °C as a calibration liquid, are given below. Plot values of the weight as ordinates and values of the angular velocity as abscissae. Draw the best curve through the plotted points and determine K for the viscometer.

(b) A liquid of unknown viscosity is placed in the same viscometer used in part (a), and the following data are obtained. Determine the viscosity of this liquid.