MCAT Physical : Viscosity

Study concepts, example questions & explanations for MCAT Physical

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Example Questions

Example Question #1 : Viscosity

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

Possible Answers:

Decreasing the volumetric flow rate of the liquid

Increasing the pressure 

Increasing the length of the pipe

Increasing the temperature

Decreasing the diameter of the pipe

Correct answer:

Increasing the temperature


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.

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