Bouyant Force in a U Shaped Plastic Tube

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SUMMARY

The discussion focuses on calculating the height of water in a U-shaped plastic tube that exerts a force of 9.8 N on a sealed cap. The relevant equation used is F = ρ * V * g, where the density of water is corrected to 1000 kg/m³. The initial miscalculation of height resulted in an incorrect value of 1998 m, which was resolved by using the correct density. The final calculation confirms the importance of accurate density values in fluid mechanics problems.

PREREQUISITES
  • Understanding of fluid mechanics principles
  • Familiarity with the equation F = ρ * V * g
  • Knowledge of unit conversions, particularly between cm² and m²
  • Basic algebra for isolating variables in equations
NEXT STEPS
  • Study the principles of buoyancy and Archimedes' principle
  • Learn about fluid statics and pressure calculations in U-tubes
  • Explore the effects of varying fluid densities on buoyant force
  • Investigate real-world applications of U-tube manometers in pressure measurement
USEFUL FOR

Students studying physics, particularly those focusing on fluid mechanics, as well as educators and anyone interested in practical applications of buoyant force calculations.

chillpenguin
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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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