Density from a viscosity experiment

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Homework Help Overview

The discussion revolves around an experiment involving a small ball dropped in a viscous liquid, where participants are tasked with determining the relationship between the diameter of the ball and its falling time to ultimately find the density of the ball. The context includes the use of a specific equation relating these variables, but several key parameters remain unknown.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between diameter and time, questioning whether a linear relationship exists and discussing the need to linearize the equation if necessary. There are inquiries about the feasibility of obtaining a numerical value for density given the unknown variables involved.

Discussion Status

The discussion reflects a mix of attempts to clarify the problem and express concerns about the lack of information needed to solve it. Some participants suggest reaching out to the professor for further guidance, indicating a recognition of the complexity of the task.

Contextual Notes

Key constraints include the unknown values of falling distance, viscosity, and the density of the liquid, which participants acknowledge as significant challenges in solving the problem.

archaic
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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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archaic said:
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.
 
haruspex said:
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.
 
haruspex said:
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. o_O
 
archaic said:
It turns out that the professor wanted to see who would really work on the problem. o_O
Sounds like a rationalisation after she/he realized the oversight.
 

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