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Density from a viscosity experiment

  • Thread starter archaic
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  • #1
363
85

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?
 

Answers and Replies

  • #2
haruspex
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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?
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.
 
  • #3
363
85
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.
 
  • #4
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85
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
 
  • #5
haruspex
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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 realised the oversight.
 

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