Solve Poiseuille's Equation: 10mL of Water in 37.50 cm h, 20.22 cm L

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AI Thread Summary
To solve for the time required to collect 10 mL of water using Poiseuille's law, the pressure was calculated as 3678.75 N/m² based on the given height, density, and gravity. The flow rate (Q) was determined to be 2.12 x 10^-7 m³/s using the formula Q = πr^4P/(8ηL). However, the calculated time (t) of 4.719 x 10^5 seconds appears incorrect, prompting a suggestion to double-check unit conversions, specifically from liters to cubic meters and milliliters to liters. Accurate unit conversion is essential for obtaining the correct final result. The discussion emphasizes the importance of careful unit management in fluid dynamics calculations.
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Homework Statement



Assume Poiseuille's law applies. If h = 37.50 cm, L = 20.22 cm, d = 0.830 mm, how many seconds will it take to collect 10 mL of water? Assume that the viscosity of water is 0.00100 Pa s, the density of water is 1000 kg/m3 and the acceleration due to gravity in the lab is 9.81 m/s2. Express your answer to 2 significant figures.



Homework Equations



Q= V/t

Q=pi x r^4 x P/8 x n x L (n = viscosity)





The Attempt at a Solution



Ok, so first I found out the pressure
P= density x height x gravity
= (1000 kg/ m^3)(0.375m)(9.81) = 3678.75 N/m^2

Then I calculated for Q using the second equation = 2.12 x 10^-7

Then I used t=V/Q = 0.10L / 2.12x10^-7
= 4.719 x 10^5

This does not seem remotely correct...eeks

Ty in advance
 
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Hint: Check yer units (1 L = ? m^3; 10 mL = ? L)
 
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