Solved: Calculating Force Needed for Archimedes' Principle

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SUMMARY

The discussion centers on calculating the force required to hold a solid cube of foam plastic underwater, given its volume of 25m³ and density of 800kg/m³. The user initially calculates the mass as 0.02kg using the formula ρ = m/V, leading to a force of 0.196N based on gravitational acceleration. However, the correct approach involves applying Archimedes' Principle, which states that the buoyant force (Fb) equals the weight of the displaced fluid, necessitating a reevaluation of the force needed to counteract this buoyancy.

PREREQUISITES
  • Understanding of Archimedes' Principle
  • Knowledge of basic physics equations: P = F/A, Fb = ρgV
  • Familiarity with unit conversions in physics
  • Basic concepts of density and mass calculations
NEXT STEPS
  • Study Archimedes' Principle in detail
  • Learn how to calculate buoyant force using fluid density and volume
  • Explore unit conversion techniques for mass and volume in physics
  • Review applications of pressure equations in fluid mechanics
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Students in physics, educators teaching fluid mechanics, and anyone interested in understanding buoyancy and force calculations related to Archimedes' Principle.

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Homework Statement



A solid cube of foam plastic has a volume of 25m^3 and a density of 800kg/m^3. How large a force is required to hold it under water?

Homework Equations


P = F/A
Fb = ρgV
ρ = m/V

The Attempt at a Solution


ρ = m/V
800 = m / 0.000025
m = 0.02kg

so F = mg = 0.02 x 9.8 = 0.196
I understand that the force required to keep it under water will be greater than this but I'm having a hard time finding the right equation.
 
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anyone ?
please
 
For starters look at the equation below that I copied.

800 = m / 0.000025

You have an error with your units.

Are you familiar with Archimedes Principle? If so, please state it.
 

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