What is the mass of the water in the stirrer supported by surface tension?

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SUMMARY

The mass of the water supported by surface tension in a hollow stirrer with a diameter of 2.0 mm at 20°C can be calculated using the formula m = 2y(πr)/g, where y is the surface tension (7.28×10-2 N/m), r is the radius (0.001 m), and g is the acceleration due to gravity (9.81 m/s2). The correct application of the surface tension equation, deltaP = 2y/r, and the pressure equation, deltaP = F/A, leads to the determination of mass. A minor calculation error was initially made, but the correct answer was ultimately obtained.

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Homework Statement


A hollow stirrer that has a diameter of 2.0 mm is inserted into a cup of water at 20∘C. The surface tension of water at that temperature is γ(surface tension) = 7.28×10−2 N/m.

What is the mass of the water supported by the surface tension in the stirrer?

Given:
d=2 mm
p(rho): 1000 kg/m^3
y(surface tension): 7.28E-2 N/m

Find: Mass

Conversions:
d=.002 m r=.001

Problem: I tried this equation, but I keep on getting the wrong answer, I am not sure if I am using the correct formula.

Homework Equations


Surface tension: deltaP=2y/r
Pressure: deltaP=F/A

The Attempt at a Solution


detlaP=2y/r
deltaP=F/A
F=mg
A=(pi)r^2
Plug them in:
mg/(pi)r^2=2y/r
Change the equation to equal mass (m):
m=2y(pi)r/g
 
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Your work looks good. What numerical answer did you get for m?
 
TSny said:
Your work looks good. What numerical answer did you get for m?
Nevermind, I got the right answer just a minor mistake. Sorry about that. Thanks for the help!
 

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