Archimedes Principle Quick Question

  • Thread starter jumbogala
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  • #1
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Homework Statement


In air, Bob's weight is 687 N. In water, it is 34.7 N.

Determine Bob's average density.


Homework Equations





The Attempt at a Solution


Is it correct to say that (buoyancy force) + 34.7 N = 687 N?

If so then buoyancy force = (density of water)(volume)*9.81 m/s

I can solve for the volume.

Then I can use (density of Bob)(volume)(9.81 m/s) = 687 N do solve for Bob's average density.

Is that right? I just want to make sure it's okay before doing the rest of the problem.
 

Answers and Replies

  • #2
kuruman
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You are on the right track.
 
  • #3
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I was just kind of confused because Bob isn't necessarily all under water. If he was half submerged, wouldn't that change things?

I guess because the question doesn't specify, I should just assume Bob's entirely under water...
 
  • #4
kuruman
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Yes, you should assume that. You cannot solve the problem otherwise, unless you know what percent of his volume is under water.
 
  • #5
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Okay, thank you!
 

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