MCAT Physical : Viscosity

Example Questions

Example Question #1 : Flow

Which of the following would tend to decrease the viscosity of a liquid flowing through a pipe?

Increasing the temperature

Increasing the length of the pipe

Decreasing the volumetric flow rate of the liquid

Increasing the pressure

Decreasing the diameter of the pipe

Increasing the temperature

Explanation:

The factors that influence viscosity are:

1. The molecular structure of the given liquid (i.e. what liquid is flowing)

2. Temperature

3. Extreme pressure

Liquids become less viscous with increased temperature. As temperature increases, the molecules move faster relative to one another and spend less time in contact with each other. This behavior causes the intermolecular forces to decrease, so the viscosity decreases.