Blood is ___ times more viscous than water.

Blood is ___ times more viscous than water.

• A. 2
• B. 4
• C. 6
• D. 8

Answer: (B)

Blood is several times more viscous than water because it contains cells, proteins, and other constituents that increase internal friction as it flows. Under physiological conditions, blood’s viscosity is about 3 to 4 times that of water, with many resources using four as a convenient approximate multiplier. The exact value can vary with temperature and shear rate, since blood is a non-Newtonian fluid and becomes less viscous at higher shear. Among common approximations, four is the best choice because it captures the typical difference without overstating or understating it.

Blood is several times more viscous than water because it contains cells, proteins, and other constituents that increase internal friction as it flows. Under physiological conditions, blood’s viscosity is about 3 to 4 times that of water, with many resources using four as a convenient approximate multiplier. The exact value can vary with temperature and shear rate, since blood is a non-Newtonian fluid and becomes less viscous at higher shear. Among common approximations, four is the best choice because it captures the typical difference without overstating or understating it.