(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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?

2. Relevant equations

P = F/A

Fb = ρgV

ρ = m/V

3. 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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# Homework Help: Archimedes principle

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