# Homework Help: Barge Depth

1. Nov 28, 2007

### Jtappan

1. The problem statement, all variables and given/known data

A flat-bottomed barge, loaded with coal, has a mass of 3.0 105 kg. The barge is 20.0 m long and 9.8 m wide. It floats in freshwater. What is the depth of the barge below the waterline?
____ m

2. Relevant equations

3. The attempt at a solution

I have no idea which equations to use or even how to solve this problem. Any help would be awesome thanks!

2. Nov 28, 2007

### Galileo's Ghost

An object (the barge) will sink until the bouyant force upwards is equal to the weight of the object. The size of the bouyant force is equal to the weight of the water that is displaced by the barge. The volume of water that is displaced will be equal to the volume of the barge under water.

3. Nov 28, 2007

### Jtappan

how do i find the weight of the water that is displaced by the barge?

4. Nov 28, 2007

### Galileo's Ghost

mass = density x volume

5. Nov 28, 2007

### Jtappan

that is the mass of water that is displaced = density of water x volume of water?

6. Nov 28, 2007

### Galileo's Ghost

yes, but remember the weight of the water will be equal to the weight of the barge. Also remember that volume = l x w x depth. You are looking for the depth

7. Nov 28, 2007

### Jtappan

ahh i totally forgot about the l x w x h thing thanks!

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