# Viscosity if liquid rhodium ball flows through

• Apr 7th 2011, 09:41 PM
sha01
Viscosity if liquid rhodium ball flows through
A researcher in Urumqi drops a rhodium ball of diameter 4.20 mm through a dilute aqueous solution of a high molar mass natural gum contained within a glass tube which has four graduations marked 10 cm apart. It is 18 C in the laboratory and the ball takes 1.86 seconds to fall between the first and second marks, 1.74 seconds to fall between the second and the third, and 1.74 seconds to fall between the third and the fourth.

What is the viscosity of the liquid?

What other information should be provided to allow you to answer the question more accurately?
• Apr 8th 2011, 12:17 AM
CaptainBlack
Quote:

Originally Posted by sha01
A researcher in Urumqi drops a rhodium ball of diameter 4.20 mm through a dilute aqueous solution of a high molar mass natural gum contained within a glass tube which has four graduations marked 10 cm apart. It is 18 C in the laboratory and the ball takes 1.86 seconds to fall between the first and second marks, 1.74 seconds to fall between the second and the third, and 1.74 seconds to fall between the third and the fourth.

What is the viscosity of the liquid?

What other information should be provided to allow you to answer the question more accurately?

You can calculate the terminal velocityof the ball from the given data (0.1/1.74 m/s). Then as this is presumably a low Reynolds number case you look up the relationship between terminal velocity, radius and viscosity and using the known data solve for viscosity.

(You can now check (or rather you could if you knew the density of the medium) and hopefully find Re<1, and preferably <0.1)

CB
• Apr 10th 2011, 03:14 PM
sha01
Thankyou very much... that is what I had worked out but just wanted to double check that I had gone about it the right way.

Thankyou again