How Does Throwing an Anchor Overboard Affect a Barge's Buoyancy?

[Brianjw]

This last problem seems to be causing me the most trouble:

Dropping Anchor. An iron anchor with mass 35.0 kg and density 7860 kg/m^3 lies on the deck of a small barge that has vertical sides and floats in a freshwater river. The area of the bottom of the barge is 7.95 m^2. The anchor is thrown overboard but is suspended above the bottom of the river by a rope; the mass and volume of the rope are small enough to ignore.

After the anchor is overboard and the barge has finally stopped bobbing up and down, has the barge risen or sunk down in the water?


By what vertical distance?

I'm not sure how to start this problem since the weight of the parge is unknown, but I'm guessing somehow that doesn't matter. Any suggestions?

 

[gnome]

Here's a question to help get you started:

When the anchor is on the deck, how much water does it displace?

 

[jamie]

if the anchor has not rested on the bottom then the answer is neither

 

[Doc Al]

another hint

if the anchor has not rested on the bottom then the answer is neither

Not true.

Brianjw: First answer gnome's question (that will get you thinking properly). Then consider all the forces acting on the barge in both cases.