In gravitation, what is the approximate viscosity value of water?

• A. 0-1
• B. 1
• C. 2-3
• D. 3-4

Answer: (B)

Viscosity measures how much a fluid resists flowing. For water at room temperature, this resistance is quite small: its dynamic viscosity is about 1 centipoise, which equals roughly 0.001 pascal-second. In the common unit context used here, that places water’s viscosity right around 1. So the best choice is the one that lists about 1. Keep in mind that viscosity changes with temperature—water becomes a bit more viscous as it cools and a bit less as it warms, but at typical room temperatures it sits near 1 cP.