Question

A piece of wood and a metal bar are placed into a tank of water. The wood floats on water, and the metal bar sinks to the bottom. If the wood and the metal have the same volume:

1. you need more information to determine the answer

2. the metal feels the greater buoyant force

3. the metal feels the same buoyant force as the wood

4. the wood feels the greater buoyant force

Answer 1

The Buoyant force is numerically equal to weight of the diplaced water when an objected is immersed in water. B = Vdisplaced water dwater g

weight of displaced liquid depends on volume of displaced liquid.

The volume of displaced water is equal to volume of the object inside the water.

Given metal and wood have same volume V.

As the metal sinks, it displaces the water of volume equal to its own volume. B1 = V dw g

As the wood floats, the volume of the wood inside the water is less than its total volume.

B2 = Vin dw g Vin  < V

Then B2 < B1

The buoyant force acting on metal is greater than the buoyant force acting on wood.

OPTION 2