# Density from a viscosity experiment

## Homework Statement:

Identify the relation between the Diameter and the time to plot a graph to determine
the density of the pellet. Would you get a linear equation? If not, linearize the
equation.

## Relevant Equations:

$$v_t=\frac{(\rho_b-\rho_l)g}{18\eta}D^2$$
The body is a small ball. The experiment consists in dropping this ball, while varying the diameter each 3 trials, in a viscous liquid and measuring its falling time: $D_i\sim t_1,\,t_2,\,t_3$.

The equation we are using is:
$$\frac{\Delta x}{\Delta t}\approx\frac{(\rho_b-\rho_l)g}{18\eta}D^2$$
I am asked to figure out a relation between the time and the diameter and find the density of the ball (I will be using Excel), but everything is unknown; falling distance, $\eta$, $\rho_l$.

Is this possible? If yes, can you please hint me to something?

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haruspex
Homework Helper
Gold Member
Homework Statement:: Identify the relation between the Diameter and the time to plot a graph to determine
the density of the pellet. Would you get a linear equation? If not, linearize the
equation.
Relevant Equations:: $$v_t=\frac{(\rho_b-\rho_l)g}{18\eta}D^2$$

The body is a small ball. The experiment consists in dropping this ball, while varying the diameter each 3 trials, in a viscous liquid and measuring its falling time: $D_i\sim t_1,\,t_2,\,t_3$.

The equation we are using is:
$$\frac{\Delta x}{\Delta t}\approx\frac{(\rho_b-\rho_l)g}{18\eta}D^2$$
I am asked to figure out a relation between the time and the diameter and find the density of the ball (I will be using Excel), but everything is unknown; falling distance, $\eta$, $\rho_l$.

Is this possible? If yes, can you please hint me to something?
If you have stated the question exactly as given to you, I would say it is asking for the procedure by which you would determine the density of the pellet if you had all that information.

If you have stated the question exactly as given to you, I would say it is asking for the procedure by which you would determine the density of the pellet if you had all that information.
No, I am actually supposed to get a numerical value at the end. I think that I will email the professor.

If you have stated the question exactly as given to you, I would say it is asking for the procedure by which you would determine the density of the pellet if you had all that information.
It turns out that the professor wanted to see who would really work on the problem. haruspex
It turns out that the professor wanted to see who would really work on the problem. 