Imagine That You Work at a Forensics Laboratory and Have

Multiple Choice

Imagine that you work at a forensics laboratory and have been asked to identify a strange, highly viscous transparent fluid found at a crime scene. The fluid has a density of 2 g cm-3. To measure the density, you drop a lead sphere of radius 2mm into the fluid, and observe that it drops at a steady speed of 8.1 mm s-1. What is the viscosity of the unknown fluid? You may assume that Stokes' law applies and that g = 9.8 m s-2.

A) 12.1 Pa s
B) 10.0 Pa s
C) 5.7 Pa s
D) 5.0 Pa s
E) 1.0 Pa s
ANS