Falling Ball Viscometers: Force Balance and Terminal Velocity

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What is viscosity?

Viscosity is defined as the resistance of a fluid to flow.

Explain how temperature affects the viscosity of most liquids.

The viscosities of liquids decrease as temperature increases.

According to the Eyring theory, what permits flow in liquids?

Vacancies in liquid permit flow in Eyring theory.

What is the Arrhenius equation used to describe in terms of viscosity?

The temperature effect on viscosity. Signup and view all the answers

At what pressure do most liquids exhibit constant viscosity?

Most liquids exhibit constant viscosity up to a pressure of 10.134MPa. Signup and view all the answers

How does viscosity of most gases change with increasing temperature?

Viscosity of most gases increases with increasing temperature. Signup and view all the answers

What forces act on a falling ball in a falling ball viscometer?

Gravitational force, drag force, and buoyancy force. Signup and view all the answers

When does a falling ball in a falling ball viscometer reach terminal velocity?

When the acceleration due to gravity is compensated by the friction of the fluid on the ball. Signup and view all the answers

Which type of viscometers are best for characterizing non-Newtonian and time-dependent behavior?

Rotational viscometers. Signup and view all the answers

What is the shear rate proportional to in rotational viscometers?

Rotational speed. Signup and view all the answers

In which region is the drag coefficient in falling ball viscometers typically measured?

Stoke’s region. Signup and view all the answers

What type of viscometer consists of two annular cylinders with a narrow gap between them?

Concentric Cylinder (Coaxial Rotational) Viscometers Signup and view all the answers

What are fluids that do not follow Newton's law of viscosity known as?

Non-Newtonian fluids Signup and view all the answers

Define apparent viscosity.

The effective viscosity of a non-Newtonian fluid under specific conditions. Signup and view all the answers

What type of fluids obey the power law model?

Shear thinning or shear thickening fluids Signup and view all the answers

What is the consistency coefficient in the power law model?

k = the consistency coefficient (Pa · sn) Signup and view all the answers

What does the flow behavior index represent in the power law model?

n = flow behavior index Signup and view all the answers

In Newtonian fluids, what is the behavior of viscosity with respect to shear rate?

Viscosity is constant and independent of shear rate. Signup and view all the answers