Simple buoyancy, density

  • Thread starter awertag
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  • #1
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Homework Statement



A large piece of cork weighs 0.224 N in air. When held submerged underwater by a spring scale as shown in Figure 13-27, the spring scale reads 0.672 N. Find the density of the cork.


Homework Equations



Fb=buoyant force

The Attempt at a Solution


i found mass by doing .224/9.8 so mass=2.286e-2 kg
then i got Fb by doing weight in air minus weight in water so Fb=-.448 N
then i did Fb=(densitywater)(volumeobject)(g) and got the volume of object so volume=4.571e-5 cubic m
last i did density=mass/volume and got the incorrect answer of 5000 kg/cubic meter

If anyone can help me, I don't know where I went wrong. Thanks very much, awe.g
 
Last edited:

Answers and Replies

  • #2
gneill
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What's an Fb when it's at home? There's no attached figure.
 
  • #3
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what do you mean at home? sorry im confused
 
  • #4
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idk if thats what you want...justr a picture, doesnt show much though
 

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  • #5
gneill
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what do you mean at home? sorry im confused

Sorry, it's just an expression. Take a look at the directions that the forces act, and re-evaluate your value for Fb.
 
  • #6
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oh ok lol. what does the expression mean exactly? Like originally?

and would Fb be equal to mg?
 
  • #7
gneill
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The expression is an inquiry as to what something (or someone) really is.

Fb is the force of buoyancy. It's opposing the weight of the object. Check your calculation for Fb.
 

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