Bouyant Force in a U Shaped Plastic Tube

AI Thread Summary
The discussion revolves around calculating the height of water in a U-shaped plastic tube that will exert a force of 9.8 N on a sealed cap. The equation used is F = ρ*V*g, where the user initially used an incorrect density value of 1 kg/m³ for water, leading to an unrealistic height of 1998 m. Upon realizing the mistake, the correct density of water, 1000 kg/m³, is identified as necessary for accurate calculations. The user is focused on isolating the height variable h to determine the required water level in the left arm of the tube. The conversation highlights the importance of using correct values in physics equations to achieve realistic results.
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Homework Statement


A plastic tube has a cross-sectional area of 5.00 cm^2. The tube is shaped sort of like a "U". The left arm is filled with water until the right arm of length 0.800 m is full of water. The right arm is then sealed with a cap that won't pop off until a force of 9.8 N is applied. What total height of water in the long arm (left arm) will put the seal on the verge of popping?


Homework Equations


F = ρ*V*g (Force = density * volume * acceleration from gravity)


The Attempt at a Solution


Trying to solve for the height h, I used the equation 9.8 N = (5.0 cm2)(1/10000 m2/cm2)(h)(1 kg/m3)(9.81 m/s2)
I'm using the value 1 kg/m3 as the density of water and 9.81 m/s2 as the acceleration due to gravity.

Isolating h, I got 1998 m, which seems way to large. I must be doing something wrong. The units work out though. I end up with meters. But the number seems way too large.
 
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Whoops I figured it out! I should be using a water density of 1000 kg/m^3!
 
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